and we find hints of that, constantly, in our lives. she was a wonderful present. >> and we're blessed to have known her as a friend. >> that's all for this edition of "dateline." i'm craig melvin. thank you for watching. watching of "dateline." i'm craig melvin thank you for watching i'm craig melvin. >> and i'm natalie morales. >> and this is "dateline." one woman, two men her husband, the air force captain, and the staff sergeant, her rendezvous man. >> he was a playboy himself. >> one man too many. then suddenly, there was >> it wasn't like bang, bang, bang, bang. it was bang, pause, bang, pause. >> which sounds more like what? execution? >> you could take it that way, yes. >> a cold-blooded killing. but who pulled the trigger? did jealousy drive someone to

murder, or did she? >> michelle theer was a brilliant, cunning, ruthless woman. >> hello and welcome to "dateline." the story you're about to see centers on a death of a military man thousands of miles from a battlefield. a dedicated officer who survived war zones only to be caught in the crossfire of a lover's triangle. here's keith morrison. >> reporter: what was she thinking when she went to the computer, when she typed in those five little words? did she not understand where those little words might lead? >> i need an ambulance. >> where are you at?

what's your name? >> michelle. >> reporter: michelle theer was, no doubt about it, dissatisfied. here she was, young, successful, attractive. and yet it wasn't exactly boredom that wals eating at michelle. after all, she was just starting a new career as a psychologist, often counseling troubled couples. >> she was relatively new with her license. i thinkat that was her first re job. >> reporter: of course michelle would havejo laughed at the ide that pretty soon now, events would propel her to such notoriety that newspaper reporters like melissa stoddard diaz would be m poking around i her past. >> michelle, from everyone i've spoken to, wanted to be somebody and really worked hard to get to where she ultimately got her degree and became a professional. >> reporter: but then michelle, even at ann early age, always seemed confident about getting

what sheem wanted. she was just 16 when she started dating marty. marty theer was a couple of yearsr older, worldly, bright, friendly, had bigly plans. heie wanted to be an astronaut. he went to the air force academy. ♪ she was 20 when she married him at the academy's famous chapel outside colorado springs. >> marty, you may kiss your bride. >> reporter: this was back in 1991, when marty was all she ever m wanted. long before she talked to that psychologist, agreed to record for the record hergi thoughts about the weird events yet to come and those happy days with marty too, of course -- >> we did everything together. he treated me really well, and i thought we had the perfect relationship. we were best friends. >> reporter: he was the dashing young officer. back then, she his lovely bride.

the future, she imagined, an endless honeymoon in which marty's airhi force career woul take them to exotic destinations all around the world. she just didn't imagine that world would beat unromantic air force outposts in oklahoma and alabama and florida, and finally fayetteville, north carolina. they came here in 1999. marty was captain theer by then, flew one of those huge c-130 cargo planes. all that time alone, not so easy on a marriage as she revealed during those tape recorded interviews with a psychologist. >> michelle talked about a few problems in the marriage, primarily growing apart over the years. marty was away for extended periods of time. she had a hard time with that. it was getting very difficult for her. she was lonely. >> reporter: sometimes he was gone for months, and when he finallynd did come home, milita families have come to know that

adjustment period all too well. they bickered. they argued about her housekeeping, his job, about having children. he wanted them, she didn't. she was worried she'd be stuck raising themd by herself in a town where she was already miserable and lonely. >> here i was in fayetteville, loser-ville, and f i had nobodyo hang up, nobody i could pick up the phone and call. >> reporter: that actually is about the time it started. harmless really, just a few key strokes to see what might happen. goes on all the time these days on the internet. sexy brunette seeks rendezvous man. and before long, her internet inquiry got a response from him. his name was john, john diamond. >> john loved women. johnve was a ladies' man. john always had girlfriends. >> reporter: so debbie, john's kid sister, could certainly see

her brother responding to a solicitation like michelle's. >> my brother's got a great personality. he's an attractive guy, and, you know, his personality makes him that much more attractive. >> reporter: then a few days afterep meeting online, they me in person at a local restaurant. >> he was charming. he was funny. talked about movies and music and things that me and marty didn't talk about. >> reporter: john diamond was an army staff sergeant based at ft. bragg andan trained as a sniper, highly regarded, decorated, had been in the service since he b was 18. >> by all accounts he was a good soldier, but h he was a playboy himself. he had been married once before and had a child from his first marriage, and he left the first wife and married, and they had a son together. >> reporter: michelle didn't know that john was still married. maybe it didn't matter, at leasa not then. she loved the sex, the attention, the excitement. >> i mean he was very attentive. he was very affectionate.

he was very adoring. yeah, it felt great. >> reporter: what made her so desirable to him? h >> i think it was just the sex. that was what he was obsessed with. he was smitten with having sex with her. >> reporter: for michelle, well, it was more lust than love. >> she felt that the affair did not take away from the fact that she loved marty. she said he was the love of her life and that she never loved john diamond. >> reporter: and marty? he was in the dark, of course. when michelle told them their marriage was in crisis and they needed to see a counselor -- >> he wouldn't agree to counseling, and i moved out. he was shocked. >> reporter: michelle got her own place andep spent much of tt steamych fayetteville summer wi john diamond. >> he was so attentive. he would rub my feet for five hours if i wanted him to. >> reporter: diamond was apparently nuts about michelle, never met anyone like her before. >> she challenged him in ways he

had never been challenged before. >> reporter: paul wolferton is a reporter with the fayetteville observer. >> she was strong and intelligent and exciting for him. >> reporter: but was he enoughd for her? apparently not because after threeap months on her own, michelle went back to marty. >> she felt that the marriage could survive despite everything that had happened, that they could make it. >> reporter: so john and michelle's six-month affair seemed to be off. but t then a few weeks later, i was apparently back on. the two traveled to the tropical island of saba, where michelle interviewed for a job at a local university. and later that fall, a romantic rendezvous at a raleigh hotel where she celebrated michelle's birthday.at but michelle, as she would later tell the psychologist, insisted it was just a relapse. >> i knew that i loved marty, and i knew that i wanted to make

it work in my heart. >> reporter: but john diamond wast. devastated, or so sad michelle. >> he said orspecifically, i'm going to kill idmyself. i can't live without you. you can't do this to me. i'm going to drive my car off a bridge. >> reporter: it was awful, said michelle. diamond kept calling, made a scene at her office in front of some students she taught. even threatened to call marty and tell him everything. so nearly a week after that romantic night in raleigh, michelle says she met john at a l local restaurant to end the affair, gently but for good. >> we had the full talk that we'll be friends. this can never happen again. he seemed very calm, very rational. >> reporter: so now it was december, time for peace and joy, christmas parties. one in particular at which the spirits flowed and the fuse burned down to its explosive

end. somebody was about to die. and somebody else wasn't taking any chances on missing. >> coming up -- >> it wasn't like bang, bang, bang, bang. it was like bang, pause, bang, pause. >> which sounds more likeus wha? an execution?s >> you could take it that way, yes. >> when "dateline" continues. [♪] did you know you can shorten your cold with cold-eeze® lozenges. cold-eeze® can shorten your cold by 42%.

it releases zinc ions that some scientists believe inhibit cold viruses from replicating. try cold-eeze® the number one best-selling zinc lozenge. introducing the future of fitness. it's every class you can imagine, live. welcome back to the mirror. you've got this john. and on demand. it's boxing... cardio... yoga... and more. it's an interactive, goal crushing...whole family...whole body fitness machine. it's so cool! the future of fitness is at home. the mirror. new advil dual action with acetaminophen fights pain in two ways. advil targets pain at the source... ...while acetaminophen blocks pain signals. the future of pain relief is here. new advil dual action. another bundle in the books. got to hand it to you, jamie.

your knowledge of victorian architecture really paid off this time. nah, just got lucky. so did the thompsons. that faulty wiring could've cost them a lot more than the mudroom. thankfully they bundled their motorcycle with their home and auto. they're protected 24/7. mm. what do you say? one more game of backgammon? [ chuckles ] not on your life. [ laughs ] ♪ when the lights go down [ laughs ] oikos triple zero has 15 grams of protein. saquon barkley needs protein to get the groceries from car to house. in one trip. i eat the protein that comes in this yogurt. ♪ ♪ it's a badge of armor of care of respect. because it means you fight for the safety of those you love. when you come into walgreens you get a flu shot that's right for you... and them

you become a flu fighter. do your part and defend your crew against the flu. ♪ walgreens ♪ start your day with secret. secret stops sweat 3x more than ordinary antiperspirants. with secret, you're unstoppable. no sweat! try it and love it or get your money back.

here in the heart of the american bible belt, on the fringe of vast, sprawling army and air force bases, like a patient, accommodating landlord, is fayetteville, north carolina. imagine most of a suburban strip mall devoted to strip clubs, and a downtown which is charming, elegant even. it's an old town, fayetteville. that tower marks the sport with north carolina ratified the constitution. sherman fought battles here in the civil war. but now it's a military town, and 160,000 acres back there is the army's ft. bragg where soldiers prepare to go to war, nestled up beside that is pope

air force base. two institutions, two professional military men, one woman. and that woman, michelle theer, now found herself caught between herself, marty, the air force captain, and her former lover, army staff sergeant john diamond, who just wouldn't go away. >> i told him, i don't want to leave my husband. i never told him i love you. i never said, i want to be with you. i mean i think i was pretty straight up. >> reporter: so now with the holiday season in full swing and a new commitment to her marriage, michelle and marty were on the road to raleigh for a night out. traveling with them was another couple from her office. >> they had gone to this christmas party that she specifically asked her boss if marty could go. >> reporter: it was sedate by office party standards and over early. since marty had to fly first thing in the morning. so now it was 9:30 p.m. marty, michelle, and the

co-workers prepared to leave the restaurant. then an interruption. michelle excused herself, made a brief phone call out of earshot of the others. then the drive to fayetteville, one hour. they dropped the other couple at michelle's office, then left for home, stopped on the way for gas. and then sitting at the gas pump, michelle told marty she'd forgotten something at the office. >> we were turn ago round and going back to the office to get some stuff that i needed that night. >> reporter: marty parked behind the office building. michelle walked up an outside staircase, disappeared inside. marty waiting in the car. apparently he got impatient, headed up the stairs to check out michelle. and that's when it happened. [ sound of gunshots ] >> reporter: she found him, she said, at the bottom of that outside stairway. she could see the blood. she ran to the nearest store, called 911.

>> somebody shot your husband? >> i think so. >> where are you at? what's your name? >> michelle. >> reporter: within minutes, fayetteville police and paramedics arrived, and they found michelle cradling her husband in a pool of blood. but it was too late. marty theer was dead. he was just 31. because marty was an air force captain, military investigators were soon on the scene as well as police, making this a joint investigation with the fayetteville p.d. both teams were eager to speak to the only known witness, michelle theer. office of special investigations agent vince pass tio. >> she said she hearded to her what sounded like three bangs of a car backfiring. >> and did she tell you what she did at that point? >> she opened the door and noticed her husband was laying at the bottom of the stairs.

>> reporter: she told him she thought she saw somebody moving in the bushes near the stairway, but she wasn't sure. >> initially, i think police were looking at perhaps a robbery of some type. >> reporter: detectives combed the parking lot surrounding area but found no one on this cold, dark december night. >> there was a man who lived behind the office building who heard the shots fired, who later said that -- he said somebody's getting murdered out there because of the order in which the shots were fired. they were very calculated. >> it wasn't like bang, bang, bang, bang. it was like bang, pause, bang, pause, a space between each of the five shots. >> which sounds more like what? an execution? >> you could take it that way, yes. >> reporter: at the top of that stairway were a few clues. bullet holes sprayed in the wall, sequins from marty's holiday suspenders littered the landing. looked like he was at the top of the stairs, shot from down

below. >> i think that's what made him roll down the stairs, and the final shot was to the back of his left ear. >> the kill shot? >> the kill shot. close range. >> reporter: they found shell casings in the parking lot. appeared to be from a 9 millimeter handgun. but there were no fingerprints, no footprints, no useful dna. but investigators did find marty's wallet still on him, complete with cash and credit cards. >> marty theer was not robbed. the other thing was that it was a very, very cold night, not a night where a prowler would be out on the streets just looking to find someone. it made it very suspicious. >> reporter: investigators couldn't imagine who would want to kill such a wonderful man like captain marty theer. but of course out in this dark parking lot, they didn't know any of what you know, not yet anyway. assuming what you've heard so far is the real story. and as you'll see, the question of what was true and what wasn't

could be very tricky indeed. >> michelle said she'd gone back to her office because she'd forgotten something. so what took so long? coming up -- >> we found a candy wrapper that had opened and in the trash can. it was almost like a scene where she had just gone upstairs and sat awaited for a few minutes. >> for what? when "dateline" continues.

it was a week before christmas 2000, and fayetteville was aglow, but not everywhere with the lights of christmas. and a few hours after air force captain marty theer turned up dead in the parking lot of his wife's office building, the news was out. and it was big. michelle theer, now marty's grieving widow, told the police she was inside her office looking for a book when she heard someone firing outside. >> by all accounts, it was an assassination. >> reporter: greg butler was a deputy district attorney in fayetteville at the time. >> someone would kill marty theer that night. there was no evidence of any robbery. there was no evidence of any other thing going on here. >> reporter: though inside michelle's office, what they found seemed, well, a little odd maybe. >> she'd gone to the bathroom. the toilet had not been flushed.

they found a candy wrapper that had been opened and in the trash can. it was almost like a scene where she had just gone upstairs and sat and waited for a few minutes because obviously to find a book wouldn't take very long. >> reporter: strange. hard to know what it meant, if anything. as dawn approached, michelle was allowed to go home. and later that morning, her boss arrived. so the cops talked to him too. >> during that interview, it came out that she was having marital problems and was having some extramarital affairs. >> reporter: funny. michelle hadn't mentioned anything about that. so detectives went to her house to follow up, and sure enough, michelle did admit having an affair with staff sergeant john diamond. michelle also said she hadn't spoken to diamond in two days. but when pressed, she remembered trying to call him unsuccessfully just before leaving that christmas party, about 90 minutes before marty was murdered. so detectives decided to check their cell phone records and

discovered -- >> they had been calling each other regularly, a minimum of 20 times a day. >> reporter: now detectives paid a visit to john diamond, who freely admitted having a sexual relationship with michelle, but claimed she was just one of many ladies in his life. and as for the night of the murder, he had an alibi. he was home with his family, watching a movie. still michelle must have harbored some sort of suspicion about john diamond, who was now a person of interest. not long after the murder, as she told detectives and that psychologist, she went to see diamond, conduct her own investigation, find out what he knew about marty's death. >> did you know anything about this? do you know anybody that had anything to do with this? he said, no, i would never do anything to hurt you. i know how much you loved him. he looked so trustful. >> reporter: mind you, as police

were soon aware, michelle had many opportunities to question her friend john after her husband died. >> there were witnesses saying he'd park down on the side street and then walk through their yards, going in the back door of her house. >> he couldn't stay away from her. >> he was going there and staying all night. >> reporter: not commonly the way widows grieve, spending the night with the person of interest in her husband's murder. but michelle told the psychologist she needed support from someone, anyone. >> as she felt more alienated from family and friends and more threatened by the police, the only person in her life that was willing to be there for her was john diamond. >> i knew that i was depressed, and i was getting more and more depressed. and i think i went to john for comfort. >> reporter: in fact, just a few weeks after marty's murder, michelle and john drove to florida for a long weekend. michelle wanted to see a former professor for grief counseling,

she said later. while diamond stayed with his sister, debbie. >> he acted as if nothing was wrong because he knows he didn't have anything to do with it. he didn't shoot him. >> reporter: so who did kill captain frank martin theer? was it possible john diamond actually executed his romantic rival? he may have had a motive. police were very suspicious. but the physical evidence was frankly rather weak. so detectives kept digging in the arcane world of phone records. boring but sometimes revealing. and one telephone number in particular caught their attention. a call from diamond to one of his army buddies at ft. bragg. >> so we asked him if diamond had any access to any weapons. he said that he loaned diamond his personal pistol. >> reporter: which just happened to be a 9 millimeter baretta pistol, the same kind of gun that killed marty theer.

>> john diamond had actually borrowed the gun from him during the time frame when the murder occurred. john diamond had possession of it. >> reporter: detectives were now convinced that diamond not only had access to a gun but maybe even the actual murder weapon. did he still have it? well, apparently not because just a short time after cops went to the home of diamond's army buddy asking about that gun, diamond made a phone call to ft. bragg and reported that his car, which he claimed to have left in the base parking lot, had been broken into. and one of the things stolen from it was a 9 millimeter handgun. >> when we got there, the passenger door had already been opened, and there was a pile of glass sitting next to the rocker panel on the passenger side. but if you looked on the unsiin, it was very little glass. >> what did that tell you? >> he had the door open when he

broke the window, and then tried to make like it was broken in. >> reporter: a bogus break-in? military police sure thought so. john diamond was arrested for admitting that he brought an unregistered gun on base. clearly diamond was now the prime suspect in the murder of captain marty theer. but was he really the killer? >> coming up, a secret about john and michelle's steamy affair becomes very public. >> she was taking him to these sex clubs and saying, it's okay. go, you know. if you want to have sex with her, that's fine. and he just -- wow, okay. >> when "dateline" continues. or. building an experience that lets you shop over 17,000 cars from home. creating a coast to coast network to deliver your car as soon as tomorrow. recruiting an army of customer advocates to make your experience incredible. and putting you in control of the whole thing

with powerful technology. that's why we've become the nation's fastest growing retailer. because our customers love it. see for yourself, at carvana.com. itchy? scratchy? family not get charmin ultra strong. it just cleans better, so your family can use less. hello clean bottom! enjoy the go with charmin. i'm a talking dog. the other issue. oh...i'm scratching like crazy. you've got some allergic itch with skin inflammation. apoquel can work on that itch in as little as 4 hours, whether it's a new or chronic problem. and apoquel's treated over 8 million dogs. nice. and...the talking dog thing? is it bothering you?

no...itching like a dog is bothering me. until dogs can speak for themselves, you have to. when allergic itch is a problem, ask for apoquel. apoquel is for the control of itch associated with allergic dermatitis and the control of atopic dermatitis in dogs. do not use apoquel in dogs less than 12 months old or those with serious infections. apoquel may increase the chance of developing serious infections and may cause existing parasitic skin infestations or pre-existing cancers to worsen. do not use in breeding, pregnant, or lactating dogs. most common side effects are vomiting and diarrhea. feeling better? i'm speechless. thanks for the apoquel. aw...that's what friends are for. ask your veterinarian for apoquel next to you, apoquel is a dog's best friend. for spending a perfectly reasonable amount of time on the couch with tacos from grubhub? grubhub's gonna reward you for that with a $5 off perk. (doorbell rings) - [crowd] grubhub! (fireworks exploding)

(- [announcer] orderingng adinner for the family?) reward it with free delivery and a side of quiet. grubhub gives you rewards for rewarding yourself with food. (doorbell rings) - grubhub! hello. i'm dara brown. here's what's happening. north korea may be preparing to test a new submarine launched ballistic missile system according to u.s. weapons experts. the test of this nature would defy president trump's threshold

requirements for continued engagement with the united states. as the 146th kentucky derby kicked off, hundreds of protesters marched to the churchill downs racetrack to demand racial justice. earlier on saturday, police intervened after a confrontation between the protesters and an armed white militia group. now back to "dateline." welcome back to "dateline." i'm craig melvin. army staff sergeant john diamond was arrested for admitting that he had brought an unregistered gun onto a military base. the same type of weapon used in the fatal shooting of his lover's husband. he was now investigators' prime suspect, but they needed more evidence. continuing with our story, here's keith morrison. >> reporter: a few weeks after the murder of captain marty theer, a fayetteville police detective named c.t. williams was asked to have a look at a couple of computers seized from

michelle theer's home, see if they might contain any clues. >> i just was looking for documents or text messages or emails. >> reporter: like an onion, he peeled back the layers of text, which though they had been deleted, reappeared under his expert touch. boxes of deleted documents, 88,000 of them, buried deep inside michelle's hard drive. and out spilled some of michelle's most intimate sexual secrets. >> she seemed to be seeking affairs with a number of people over time. she was looking for an alternative lifestyle. she was seeking a partner and esco escort. >> that would be carolina swingers. within michelle's lengthy list of emails, detectives also discovered that not so innocent inquiry she typed seeking a rendezvous man. that was john diamond, of course, who replied, and who the email trail revealed quickly

joined michelle in the lifestyle. >> she was taking him to these sex clubs and saying, it's okay. go, you know, if you want to have sex with her, that's fine. go. i'm fine with it. and he just -- wow, okay. >> reporter: but as investigators sorted through the sexually charged email, they could plainly see a story as old as time. john diamond fell head over heels in love with michelle. >> here's her little puppy to be controlled any way she wanted to control him. >> he was like the child in the relationship. >> whatever she wanted, he was at her beck and call. >> reporter: hundreds upon hundreds of lurid, love sick emails. john diamond appeared to be a man obsessed. i can't wait until you come back so we can take care of each other. you know, sex, sex, sex and of course, more sex. i know that we're meant to be together and are kindred soulmates. i will always love you no matter how you've hurt me. >> you could tell it not only changed from a sexual

relationship to a completely, totally enamored with her any way you can imagine. >> and he was getting desperate. >> he wants to be with her. his plans were to be with her. he's willing to do anything to keep the woman he's in love with. >> anything? perhaps even kill the man who stood between him and michelle? >> she was beginning to set him up. she was playing his emotions. >> she was pushing him away kind of. >> pushing him away in some ways but without really completely pushing him away. i think she was manipulating him at that point. >> manipulating him into murdering her husband? but why would she want to do that? >> there was a $500,000 life insurance policy that had been taken out in 1989 on marty theer. >> and the sole beneficiary, michelle theer. john duiamond's family was outraged at such a theory. they were convinced michelle typed all those emails and sent them to herself, to steer investigators away from her and to diamond, so he'd take the

rap. >> he never once expressed a love feeling about her to me. so unless you come to me with a handwritten letter that he was obsessed with her, i'll never believe that. >> how do you know that? >> because he told me he did not want to marry her. he did not want to spend the rest of his life with her. >> reporter: according to debbie, it was michelle who was obsessed with john, and never more so than when she gave debbie two wedding rings to take to her brothers, who was by this time locked in the brig. >> i think maybe she was obsessed with him in the point that she couldn't control him, that she couldn't, you know, control the situation. >> she wanted to control it, and if she gave him a wedding ring and he wore it, wouldn't that give her all kinds of reason to claim that he would do anything for her, including kill her husband? >> it could be. i don't know. what i got from him after he was arrested was he didn't want anything to do with her, nothing. >> reporter: with or without michelle, john was in big

trouble. so he lawyered up with prominent fayetteville attorney coy brewer. >> i believe that he was an innocent man wrongly accused, that any rational interpretation of t . >> but military investigators were convinced diamond was the trigger man and decided to quickly proceed with their case against them. and michelle remained free. and what did she do? oh, she left town. >> i think she planned to kill her husband a long time ago. i think she waited and researched and waited for that right person that would look and fit the part to pin it on. >> reporter: if that was true, michelle's plan was working perfectly because in a few short weeks, john diamond would be on trial for murdering her husband. >> coming up, the prosecution's case against john and the

defense's case against michelle. >> michelle theer was a brilliant, cunning, ruthless woman who wanted her husband dead. >> when "dateline" continues. or? secret aluminum free helps eliminate odor instead of just masking it. and is made with three times more odor fighters. with secret, odor is one less thing to worry about. secret. an extra 15% credit on car and motorcycle policies? >>wow...ok! that's 15% on top of what geico could already save you. so what are you waiting for? idina menzel to sing your own theme song? ♪ tara, tara, look at her go with a fresh cup of joe. ♪ gettin' down to work early! ♪ following her dreams into taxidermy! oh, it's...tax attorney. ♪ i read that wrong, oh yeeaaaah! geico. save an extra 15 percent when you switch by october 7th. ♪ give it up for tara!

that's why i've got the power of 1,2,3 medicines with trelegy. the only fda-approved, once-daily 3 in 1 copd treatment. ♪ with trelegy and the power of 1, 2, 3, i'm breathing better. trelegy works 3 ways to open airways, keep them open, and reduce inflammation for 24 hours of better breathing. trelegy won't replace a rescue inhaler for sudden breathing problems. trelegy is not for asthma. tell your doctor if you have a heart condition or high blood pressure before taking it. do not take trelegy more than prescribed. trelegy may increase your risk of thrush, pneumonia, and osteoporosis. call your doctor if worsened breathing, chest pain, mouth or tongue swelling, problems urinating, vision changes, or eye pain occur. think your copd medicine is doing enough?

maybe you should think again. ask your doctor about once-daily trelegy. we know times are hard and we're here for you. find support at trelegy.com. did you know you can shorten your coldrd and we're [♪]e for you. with cold-eeze® lozenges.

cold-eeze® can shorten your cold by 42%. it releases zinc ions that some scientists believe inhibit cold viruses from replicating. try cold-eeze® the number one best-selling zinc lozenge. in the dead center of ft. bragg, north carolina, is a nondescript red brick building. this is where army staff

sergeant john diamond found himself a prime suspect in the murder of air force captain marty theer. >> military justice is much swifter than civilian justice. so he goes to the article 32 hearing, which is like the grand jury. they immediately find cause, and they charge him. >> reporter: and nine months after the murder, in a small ft. bragg courtroom, diamond went on trial before a military jury. >> diamond was very, very cocky at the beginning. he would laugh and joke with reporters in there. he was just so sure that he was going to be acquitted. >> reporter: but john diamond wasn't the star of his own trial. michelle was. she was free as a bird then, though still under investigation by fayetteville civilian homicide cops. and here she was called to testify at her former lover's military trial. >> she shows up. her hair is now like a red color that she's colored it. she's lost a bunch of weight,

and she's got a gaggle of media following her into the building. >> reporter: it was all image, no substance. michelle took the stand but took the fifth. the prosecution's case against diamond, its accusation was simple. driven by his obsession for michelle, he conspired with her to kill her husband by borrowing the gun, arranging to be in a position in that dark parking lot, waiting until marty theer had placed himself in the kill zone at the top of the staircase outside michelle's office, and fired the five shots that killed him. as for diamond's alibi, that he was home with his wife watching a movie, that now ex-wife came to court and told the jury that the evening wasn't quite like that. halfway through the movie, his phone rang, she said, and suddenly he was gone. and what's more -- >> her mother heard him come home, you know, in the wee hours and wash clothes. >> reporter: true? maybe not, said defense attorney coy brewer.

her story changed after she talked to police. >> she was afraid of the government. i don't think that she was telling the truth. >> reporter: had she been pressured? besides, said the defense, there was no dna, no footprints, no fingerprints to prove diamond shot marty theer. and anyway, diamond was a trained sharpshooter, but the shots that felled marty were sloppily, badly aimed. must have been the work of an amateur, said diamond's attorney, an amateur like michelle. >> michelle theer had asked for the gun several days before the murder. she had told him that her husband was abusive, that she was afraid of him. so he gets the gun, he gives her the gun. now, he didn't think she was going to kill him with the gun. >> did she just use him and know he was somebody he could use to serve her purposes? >> she set this up to kill her husband because she wanted the insurance money and for sergeant

diamond to take the fall. michelle theer was a brilliant, cunning, ruthless woman who wanted her husband dead. >> reporter: the military jury, however, didn't see it quite that way. >> the verdict was swift. guilty as charged. and from that moment on, his demeanor changed. i mean it was like somebody just sucked the air out of him. the john diamond full of bravado and ego just shriveled away. >> reporter: diamond was sentenced to life in prison without parole. at the time, his family was furious, convinced he was framed. >> you don't expect to be convicted on theory and myth and what ifs. show me blood. show me a gun. show me the timeline that works. show me those facts. i'll believe till the day i die that she killed her husband, that she planned to have my

brother go down for it so she could live this happy, wonderful life. >> reporter: curious thing that. as john diamond settled into a life in prison, people in fayetteville could see to their great disapproval that michelle went on with a life uninterrupted, and then quite suddenly, they didn't see her at all because michelle theer disappeared. >> coming up, michelle wasn't just a missing woman. she was also now a wanted woman. >> there was some speculation that she was ticked off that she had been indicted because she seemed to really sort of fall off the face of the earth. >> when "dateline" continues. fights pain in two ways. advil targets pain at the source... ...while acetaminophen blocks pain signals. the future of pain relief is here. new advil dual action.

thereyou're not good enough hard to control but i am enough music and i know what i'm made of put your skin in the game with a razor that puts your skin first venus my skin. my way. special guest flo challenges the hand models to show off the ease of comparing rates with progressive's home quote explorer. international hand model jon-jon gets personal. your wayward pinky is grotesque. then a high stakes patty-cake battle royale

ends in triumph. you have the upper hands! it's a race to the lowest rate, and so much more. only on "the upper hands."

welcome back to "dateline." shortly after john diamond was convicted in the murder of her husband, michelle theer did something unexpected. she left fayetteville, north carolina, without a trace. authorities weren't done with her yet, but would they be able to track her down? here with the conclusion of "deadly ambush" is keith morrison. >> reporter: leavenworth federal prison. doing time doesn't come much harder than it does here. this is where john diamond was serving a life sentence for murdering air force captain marty theer. but his former lover, michelle, seemed to have dropped right out

of sight. where was she? people weren't seeing her around fayetteville. the d.a., meanwhile, was convinced she must have conspired with john diamond to kill her husband. she was the brains. he was the brawn, or in this case, the shooter though it was all circumstantial, said greg butler, it was persuasive. >> there was a significant amount of evidence. i don't think there was any question as to who was involved, diamond and her together. >> reporter: the evidence, the life insurance, the affair, the aaccess to a murder weapon, those emails, the cover-up. taken together, it was enough to convince a grand jury. and finally in may of 2002, nearly 18 months since her husband was killed, michelle theer was indicted for first-degree murder and conspiracy. but arrested? no. why? >> there's some speculation that she was tipped off that she had been indicted because she seemed

to really sort of fall off the face of the earth right before that came down. >> reporter: michelle theer vanished. no one, not even her family, knew where she was. lauderdale by the sea is a charming little town just north of miami. quaint and quiet. low profile. in the summer of 2001, cindy geesey, a local landlord, met with a woman who wanted to rent a room in her cottage. >> she gave her name as liza pen dragon. she seemed well spoken, intelligent. she told me she was on the run from an abusive boyfriend in california. >> reporter: she made friends around the neighborhood. before long she had a new beau. liza -- it was really michelle of course -- kept in touch with her family very carefully, secretly. she only called on pay phones, for example, and that rarely. >> two months after michelle arrived in florida, she asked

her boyfriend to call her parents, pass on a message. use a pay phone, she told him. and maybe he forgot or perhaps she didn't tell him why, but he called from his parents' house phone. u.s. marshals were monitoring. they looked up the number that had called michelle's parents. >> and the database told them that this woman had a son in his mid-20s who lived in south florida. >> reporter: did he know the missing michelle? the cops found him, staked him, then followed him to that little white beach cottage, where he and michelle were in for a big surprise. >> following a developing story out of florida. a woman wanted for the murder of her husband, a pope airman, has been arrested in florida. >> at the time of her arrest inside the apartment, we found magazines describing ways to go undercover in the united states, obtain new identity. >> reporter: books too on

learning spanish, travel guides for several latin countries, an array of fake i.d.s, and then there was michelle's appearance. >> she had changed her appearance, cut and dyed her hair, had some plastic surgery done. >> do you have anything at all to say? >> reporter: a few days later, michelle, her face still red and swollen and smeared with ointment from cosmetic surgery, was driven back to fayetteville. she was charged with first-degree murder and locked up without bail. and two years later, in september 2004, after turning down a plea deal that would have imprisoned her for ten years, the prosecutor laid out his case against michelle theer. the proof, for one thing, all those intimate emails, which showed, said the prosecutor, how michelle manipulated diamond and made him her fall guy. >> he got down to the point he

was so upset if he helicopter ha -- couldn't have her, he was wilting to kill himself. michelle directed him. it got to the point where he was willing to kill marty. >> reporter: that point arrived, said the prosecutor, after that office christmas party, when michelle called diamond to tell him that she and marty were heading to the kill zone, the parking lot of her office building. but she needed him there alone. so after they dropped two co-workers at the lot, mushl made a crucial move that linked her to the murder. remember, the theers began driving home, stopped for gas. but then michelle by her own admission had marty return to the office, supposedly to pick up some work she needed. and while she dawdled in the office, marty became impatient, went up those stairs to check on her. and thus walked into an ambush. >> when they left, there would have been no way for that shooter to have any reason to believe that they were coming back unless he had known through

prior conversation with michelle theer, she was going to bring him back to that location, go up into her business, live him outside the door so he could then murder her husband. >> that was really your smoking gun. >> that was the smoking gun that tied her to it. >> reporter: michelle did not testify, nor did john diamond. her attorney belittled the state's evidence as thin and circumstantial. among those speaking for michelle, the psychologist. she was hired by the defense to interview michelle about her relationships, to testify as an expert witness. those were the recorded conversations, excerpts of which you heard earlier. the doctor told the jury michelle wasn't manipulating diamond by stopping and starting their illicit romance. no, it was something else. >> when somebody's in a long-term affair, there does tend to be a pattern of pulling away and then coming back together, an inability to be decisive. that's not unusual with affairs.

>> reporter: besides, claimed the defense, being involved with another man didn't mean michelle was also involved in murder. the two sides battled through three months of trial time, from labor day past thanksgiving, an 11-week trial. three-hour deliberation. the verdict, guilty. >> she stood up. they put the handcuffs on her, and she walked out of the courtroom, and she never looked back into the courtroom area, not even toward her family. >> reporter: michelle theer now sits in a north carolina prison, halfway across the country from her co-conspirator, john diamond. today these former lovers share only one thing, life without parole. his supporters are heartfelt in their certainty that she was the bad one. she did it all. he didn't do anything. >> and her supporters all blame him and say that he did it without her knowledge because he was in love with her and she was breaking up with him.

>> reporter: michelle theer rolled the dice. she turned down a deal which would have released her before long. instead, the woman who followed her dissatisfaction to an internet romance went on trial. and as a result, will i'm craig melvin. i'm natalie morales. this is "dateline." she was there. >> she'd walk into the room and kind of brightened. >> and then she wasn't. >> my initial reaction was what happened. >> the mother they adored. missing. in her place, a trail of blood. >> my biggest fear was we were going to find her. >> what police found instead was a puzzle. >> in my 28 years, i have never