sense. i loved my husband then. i love my husband now. we had a good marriage, still have a good marriage. reporter: you think your marriage will survive this? well, yeah. i have no doubt that will. it survived 10 and 1/2 years of separation. it survived a trial, prison. i don't know what else there could be. that's all for this edition of "dateline." i'm craig melvin. thank you for watching. hello, i'm craig melvin, and this is "dateline." hello, i'm craig melvin, and this is "dateline." he says, there are these little falcons. and he goes, they watch over the dead, jimmy. he goes, they do. craig melvin: what if someone asks you to risk your life-- jimmy keene: what if i get shanked? what if i get killed?

craig melvin: --to go undercover into one of the country's most dangerous prisons-- jimmy keene: once they stepped out the door, i was on my own. craig melvin: --to help catch a killer. she had such a zest for life. craig melvin: young girls were being murdered. i can't imagine sending my daughter off to school and never seeing her again. craig melvin: and investigators needed help to get a confession. larry beaumont: if anybody could pull it off, he would probably be the one to be able to pull off. craig melvin: but this snitch was different. he was already a convicted felon. if it worked, he could win his freedom. if he didn't, he could lose his life. - they had your back. - they had my back. at least you thought. that's what i thought. [suspenseful music] hello, and welcome to "dateline." jimmy keene was a smooth talking convict serving a 10 year sentence when he was offered an unusual deal. if he'd help prosecutors pry a confession from a suspected

serial killer, including the location of the victim's body, he could walk away a free man. it was dangerous undercover work requiring jimmy to spend months behind bars of a federal prison for the criminally insane. getting in was the easy part. getting out alive would be much harder. here's lester holt with the "inside man." [suspenseful music] lester holt: two enemies who didn't trust each other faced off across a table. one of them in handcuffs was a clever con named jimmy keene. the other a hard charging prosecutor. in court he called me the john gotti of kankakee. lester holt: the prisoner was worried sick. larry beaumont, the prosecutor who had just convicted keene and put him behind bars, suddenly wanted to talk-- a top secret meeting no less. what more could he do to jimmy? jimmy keene: he was the last person i expected to hear from.

he was my biggest fear. [suspenseful music] lester holt: but keene's fears went off the charts when the prosecutor slid an accordion file in his direction. on top was a grisly photo of a dead girl. i flipped to the next page, and here's another young dead mutilated girl. and i'm thinking, whoa, wait a second. he's probably thinking at this point that you're about to charge him with something else. yeah, because you know, i mean, i had been pretty rough on him in the initial prosecution. lester holt: jimmy was in the dark. he had no idea of the crazy scheme beaumont had in mind. and he says, jimmy, he says, listen. he goes, this is something that we have another person on. he has killed many, many young women. and i personally think you're the one that can help us with this. lester holt: this turned out to be an investigation to try and catch a suspected serial killer. beaumont, an outside the box thinker, believed this convict, jimmy keene,

was the one who could somehow crack the case, taking on a unique and deadly mission. jimmy keene: i realized how serious it was, and i also realized the danger of it. lester holt: but what he couldn't know was how such a daring mission would change his world, and the person he was forever. if this all seems fodder for a hollywood movie, brad pitt would agree. the megastar who was benjamin button then "moneyball's" billy beane considered playing none other than jimmy keene. [light instrumental music] jimmy keene: brad pitt likes the fact that this guy, jimmy keene, risked his life to try and find what he could find. [ominous music] lester holt: clearly, this guy is one of a kind-- charismatic, conceited, courageous, and complicated. [light instrumental music] from an early age, he had the personality, charm, and cockiness that made him dream that a hollywood star might one day want to play him in the movies. [crowd cheering]

his first big brush with fame came on the football field. i heard called you "the assassin" in football. [laughs] that was a good thing, i take it? yes. i was taught by my dad at a young age-- he said, son, he goes, if you don't hit that guy first, he's going to hit you and hurt you first. [whistle blows] lester holt: a superstar athlete and mr. popularity in high school, jimmy seemed to have it all as a big fish in the river city of kankakee, illinois. a blue collar town south of chicago. i was most valuable player. i was captain the team every year that i played. lester holt: jimmy grew up in the shadow of his father, big jim. a giant of a man who was a cop, fireman, and hero to his son. jimmy keene: he's my best friend. yeah. he was my backbone in pretty much everything i did. lester holt: but all of keene's grand potential would be put in peril by a terrible choice he made. as a teenager, he began selling drugs. [suspenseful music] he started small, pedaling bags of marijuana here in this kankakee park. then he expanded to cocaine. and at the tender age of 17, he moved to chicago,

where the business and profits exploded. he was now a big fish in a bigger pond-- lake michigan to be exact. he was his own in crowd. fast cars and souped up living. all the hot spots, all the big nightclubs-- all the owners i was in tight with. i would come in there and have carte blanche in every place that i went to. were you're feeling invincible? yeah. there was a certain point where i would say there was an invincible feeling. did your pop know what you were doing? did he suspect? he didn't suspect it until much, much later. lester holt: it would be a rude awakening for both his dad and jimmy that day in 1996 when jimmy was just relaxing at one of his chicago homes. and all of a sudden, kaboom. the whole door just blew off the hinges and come flying into the house. and all of these dea, fbi, and locals all came in in single file line with their automatic weapons pointed at me. (imitates officers) freeze.

get on the ground. get on the ground. lester holt: he had been caught in a drug sting spearheaded by that hard nosed federal prosecutor, larry beaumont. we scooped him up in an operation that i ran. we called it operation snowplow. lester holt: and in court, beaumont showed keene no mercy. he was coming at you on all fours though? - oh yeah. - wasn't he? oh god. i mean, he was-- he was a bulldog. lester holt: jimmy was convicted and slapped with a 10 year sentence. larry beaumont: it was a pretty stiff sentence and i knew he didn't expect to get 10 years in that case. your father was in the courtroom? right. i knew i had let him down in probably one of the biggest ways you could let somebody down. [suspenseful music] lester holt: keene's future was bleak. he faced 10 years away from his glamorous life, the fancy cars, the big bucks. but in 1998, just when all hope seemed lost, his old nemesis, beaumont, came to him with an offer of freedom attached to that accordion file he'd slid across the table. in return, keene would have to agree to risk everything

and become an undercover informant in one of the roughest prisons in the country. the maximum security lockup in springfield, missouri. [metal doors clang] [eerie music] it was a psychiatric prison with both hardcore killers and the criminally insane. these people all have life sentences. they're all in there, and they're crazy loons. and they have nothing better to do, but to try to hurt you or kill you just for some fun. lester holt: if he accepted beaumont's offer, keene's target would be the suspected serial killer, a mysterious man in a van. craig melvin: coming up-- [upbeat music] every picture tells a story-- investigator: when i put the picture down, he flinched and raised his arm up and refused to look at the picture. craig melvin: --when "dateline" continues. the freestyle libre 3 plus sensor tracks your glucose in real time, and over time

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several years before jimmy keene's arrest and conviction, without daily hiv pills. his drug business was booming. and his personal life, as he tells it, was nonstop fun and games. there were a lot of hot clubs here in the '90s. this was a place where you were doing business as well. lived, worked, and played right here. yes. and it was a good time. lester holt: back then, he had no idea about the danger lurking 150 miles south and a lifestyle away that would change his life forever.

rural tranquil georgetown, illinois was where terry roach, and her husband, lauren, were raising their 15-year-old daughter, jessie, and two other children. far removed from big city crime. everybody knew who everybody was so they were more conscious of what was going on, usually. you could count on somebody to get after your kids if they needed it. lester holt: in 1993, jessie was a high school sophomore devoted to home and family. jessie was really very much of a homebody. so one bike ride up the road and back, she was done. and then she would be watching "gone with the wind". lester holt: one monday in september, jessie went out for a bike ride. but just minutes later, her sister noticed jessie's beloved bike down on its side in the middle of the road. not on the side of the road, middle of the road. yeah, she would have put the kickstand down and stood the bicycle up. she would never lay the bicycle down. and i immediately went down there, and there's a bicycle.

it was like, i knew something was wrong. lester holt: gary miller was the deputy sheriff dispatched to the scene. the more we learned about the family and the girl's background, we just didn't feel that she was staying away by choice. lester holt: the haunting image of a bike tipped over and abandoned terrified all the investigators and of course, jessie's family. i mean, you never lose the hope for them not to come walking in. you know, you still hope that-- i mean, we knew she was not just going to walk away. lester holt: after six weeks, jessie's parent's worst fears were realized. her body beaten and sexually violated was discovered in a cornfield. it can never be easy telling a parent that their child is dead. no, it wasn't. but at least we were able to tell them, this is her, she's gone. we were able to erase all doubts. lester holt: gary miller had a murder case to solve.

and it was now a federal case involving prosecutor larry beaumont as well, since jessie's body actually had been found across the illinois state line. for the next year, miller did lots of legwork, but to no avail. everyday you get up, are you thinking about this case? oh, everyday. what have i missed? exactly. i know this case really shook him from the beginning. and he would check any and all leads that would involve young girls and kind of run them down. lester holt: then in late 1994, miller's persistence finally paid off. a man in a van had been reported chasing two teenage girls in jessie's home town of georgetown. miller traced the van to a man named larry hall from wabash, indiana, a three hour drive from georgetown. is your heartbeat starting to pick up a little bit now? oh yeah. you know, i'm thinking, this has got to be checked out. lester holt: miller learned that hall was a gung ho civil war re-enactor, a pretend union soldier

who traveled the midwest to fight fantasy battles. miller immediately drove to wabash to interview hall, who wasn't saying much. so miller showed him a photo of jessie roach. when i put the picture down, he flinched, raised his arm up, and turned in his chair, and refused to look at the picture. lester holt: convinced larry hall was hiding something, miller became obsessed with making a case against him. days later, back in illinois, miller turned up a huge lead. he found witnesses who vividly remembered hall from a revolutionary war reenactment in the georgetown area the very weekend before jessie was abducted. to them, hall stood out for his bushy mutton chop sideburns, but also, for playing a soldier who was fighting the wrong war. he was wearing a civil war uniform, and he had a civil war hat. at a revolutionary war re-enactment.

exactly. lester holt: armed with his new information, deputy sheriff miller returned to wabash for a second crack at hall. this time, he pressed his suspect harder, stressing that hall's fellow re-enactors had seen him near georgetown. he came along to the point where he said, well, i go to so many reenactments, i could have been there, and just-- you know, i just don't remember because i go to a lot of them. he's giving a little more ground. right, yeah. lester holt: miller sees the opening and kept at it. finally, he said, hall came clean, and confessed that he abducted, sexually violated, and strangled jessie roach to death. how much detail did he give you about the killing of jessica roach? very good detail. what he actually did and what took place. lester holt: not only that, miller says larry hall confessed to other killings, including a coed from indiana wesleyan university in nearby marion, indiana named tricia reitler.

he did say he was involved in reitler. lester holt: deputy sheriff miller didn't know much about tricia, so he called on the local indiana police who had been handling that case. but when marion detective jk and other indiana cops arrived, hall was suddenly telling a much different story. he denied confessing to any killing, including jessie's and tricia's. what's more, he claimed it was all a misunderstanding about disturbing dreams he had. he takes us out to a location where, in my dreams, i strangled her here, and left her lay here. we searched the woods, we searched the area, and never really found anything. lester holt: the indiana cops who are familiar with hall were not at all surprised by his actions. some of them, like jk, thought hall might be a wannabe, a pretender who gets his kicks from confessing to crimes he didn't commit. is it possible he's simply obsessed with these cases, but not involved? there's no doubt in my mind that he

does follow these cases, that he does read, and is attracted to cases all over the country. you know, so the question does come, you know, is he a wannabe. lester holt: deputy sheriff miller and prosecutor beaumont however, felt certain they had a real killer on their hands. a serial killer with a unique mo. he would drive cross-country to re-enactments where he played fantasy soldier, then prey on young women, and kill for real. well, the fbi are discovering girls that were in fact missing at these various areas at the time larry hall would have been there. lester holt: but the only case for which prosecutors had sufficient evidence was jessie roach's. larry hall was arrested in connection with her death, even though he denied making that confession to miller. hall went on trial in 1995. as a prosecutor, what's the best card you're holding? we had a statement, his confession. said he did it. beaumont called deputy sheriff miller to the stand

to testify that hall had indeed admitted that he abducted and killed jessie after he spotted her with her bicycle. she was walking her bike at that point. lester holt: miller testified that in his confession, hall gave him a detail that only the killer would know-- that jessie was not riding her bike, but walking it. a safety precaution the roachs insisted she follow when she was on their narrow road. that was never in the press, that she was walking her bike that day. right. when you heard that, did that give more credence to this story? oh yeah. that just sealed it for me. i knew. i knew that he was the one. a jury unanimously agreed. it took just three hours to convict larry hall. but prosecutor beaumont believed this was just the tip of the iceberg. he felt certain hall was a serial killer, and now he had to find a way to prove it. so he began investigating tricia reitler's abduction, a case that wasn't his for a family he

didn't even know. i can't imagine sending my daughter off to school and never seeing her again. lester holt: and he came up with an outside the box scheme to get hall, which would risk the life of a charismatic convict he had just put away for dealing drugs-- jimmy keene. what happens when i've got to deal with all these crazy killers and stuff? you know, what if i get shanked, what if i didn't killed. i mean, am i going to survive this? jimmy's get out of jail free card comes with a hefty price. coming up. they had your back. they had my back. at least you thought. that's what i thought. lester holt: when dateline continues.

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i have one, too. i'd be so lost without mine. we are talking about mentors, right? yes. a mentor can guide you. support you. and unlock your potential. being a mentor can be just as life-changing. you can create opportunities. and inspire the next generation. helping someone find their path can transform your own.

so find a mentor. or become one. wait, can i do both? you know what? let me ask my mentor. of course, you can. bring someone along on your journey. and see where it takes you. people typically don't admit murder-- sexual assaults and murders-- to police officers unless in fact, they probably have done it. so is clear, we felt, he was responsible for the tricia reitler disappearance. she had such a zest for life. and she'd walk in the room and everybody knew she was there. lester holt: tricia reitler, a 19-year-old psych major at indiana wesleyan university, was on her way to becoming a family counselor. her goal was to be able to put families back together again. lester holt: then in march, 1993, donna and gary reitler receive that late night phone call every parent dreads. a cop from marion, indiana was on the line.

he says, do you know where tricia is? in my heart, you know, i knew that something was drastically wrong. lester holt: tricia had walked to an off campus supermarket and never returned to her dorm. more than 25 years later, her parents are still waiting. we have no answers. and somebody out there-- that's what eats at me-- somebody out there has an answer for us. lester holt: tricia reitler wasn't even prosecutor beaumont's case, but he was deeply moved by her parents. and that was always a horrible crime to me. i knew about the facts of the case, and i knew about the family. i never met them, but i read all the newspaper articles and accounts of them asking for help. lester holt: beaumont felt certain that suspected serial killer, larry hall, was responsible. not only did hall live 25 minutes from indiana wesleyan, he'd been identified chasing two coeds there just a week after tricia went missing.

so in the summer of 1995, a month after convicting hall for jessie roach's murder, beaumont was leading a search for tricia. it was in those same indiana backwoods where hall had told indiana authorities he dreamt he killed and buried tricia. i wanted to feel like i did everything i could to see if we could find her body. lester holt: but after two days, searching in sweltering heat and humidity, tricia's body didn't turn up. larry beaumont: we couldn't find anything. doesn't mean it wasn't there. lester holt: then beaumont decided to try something completely different. larry beaumont: i came up with the idea of putting somebody in the prison cell with him to see if we can get him to tell us what he did with tricia reitler. they all think you're crazy? most people did think i was crazy, yeah. but i was able to convince them that we should do it anyway. lester holt: enter jimmy keene, the drug dealer beaumont had just convicted and sent to a low security prison. why did he stick out in your mind? because i knew he was kind of a con man.

he was smart. i knew if anybody could pull it off, he would probably be the one to able to pull it off. he says, you've been trained in martial art. he goes, you can go into a dangerous environment where a lot of people can't. and you can maintain and protect yourself in an environment like that. lester holt: in return, beaumont offered jimmy freedom. but first, jimmy would have to exact more than a confession. i told him, unless we found the body, he would get no credit. no body, you get nothing. lester holt: jimmy was skeptical. he was a drug dealer, not a criminal profiler. and he knew this was a mission impossible. he said no. but then fate intervened. jimmy's dad suffered a stroke. weeks later, frail and sickly, he came to visit jimmy. my dad was in a wheelchair. now this is big jim, the guy that had been superman to me my whole entire life. we cried through the window to each other and we talked for a while. and he didn't even know about the offer. nobody knew about it. lester holt: jimmy now realized that he had a one time only

opportunity to fix the mess he'd made for himself and get out while his dad was still alive. as soon as we were done with the visit, i called my lawyer, i said, tell beaumont i'm going to take him up on his offer. lester holt: the mission was on. so on august 3, 1998, federal marshals escorted jimmy into the psychiatric prison. once they stepped out the door, i was on my own. lester holt: jimmy's cover story was that he was a convicted weapons runner, whose 40 year sentence pushed him over the edge and landed him in the psych prison. a psych prison filled with killers. his one inside contact, the chief psychiatrist, couldn't protect them. nor could his outside lifeline, a female fbi agent who visited as his girlfriend to monitor his progress. i did have a hotline to her too. so if i get caught in a dangerous situation, i could get a hold of her. and the deal was they'd have me out of there in 24 hours. - they had your back. - they had my back. at least you thought.

that's what i thought. lester holt: when keene's mission began, it was all about him, his shot at freedom. he had few feelings, if any, about tricia reitler or her family. all he wanted was to get in and out with tricia's location, and as fast as possible. day one, breakfast in the mess hall. jimmy zeroed in on larry hall. i was waiting with my tray, and i look over, and there he is 20, 25 feet away from me, sitting there all by himself. it felt like a magnet was compelling me to come to him. and finally, i bumped shoulders with him on purpose. lester holt: jimmy explained he was a brand new inmate needing directions to the library. hall obliged. i kind of slapped him on the shoulder, i said, thanks a lot. i said, i appreciate that from a cool guy like you. lester holt: after that, they occasionally talked. but the next step came when jimmy was invited to join hall's breakfast club. which in the prison system, is a big thing of who you're invited to have your breakfast with.

lester holt: keene thought he was making progress, but then prison politics got in the way. i left out the chow hall one morning, and a few really big muscular guys came up to me. and they said, hey, the old man wants to talk to you right now. right now, he wants to talk to you. lester holt: the old man with celebrity mafioso vincent "the chin" gigante, also known as the oddfather, who used to wander around new york city in his bathrobe pretending to be nuts. hey goes, hey boy, what's wrong with you, what's wrong with you? why are you hanging around all them baby killers over there for? he goes, you hang with us from now. he goes, you hang around them people, he goes, you know, maybe somebody comes up and puts a knife in your back. you know? and he'd be at my cell early in the morning, jimmy, get up, get up. we're going to go out and play some basketball. what about breakfast? well, we'll go out and get a round of basketball in first, then we'll go have breakfast. that's all very nice except you're trying to get out of prison. exactly. lester holt: the chin was taking up jimmy's valuable time, making it harder to even talk to hall.

but then he learned hall's favorite show was america's most wanted. so one saturday night in the tv room, jimmy would make a daring move, putting his body on the line just to gain larry's from. coming up, jimmy's new best friend shares a nightmare. it was probably the hardest thing i've ever done in my life. to listen to this kind of stuff and just rip him apart. lester holt: when dateline continues. my name is brayden. i was five years old when i came to st. jude. i'll try and shorten down the story. so i've been having these headaches that wouldn't go away. my mom, she was just crying. what they said, your son has brain cancer. it was your worst fear coming to life.

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hi, i'm richard lui with a news update. thousands of travelers taking to the road and skies ahead of the christmas holiday. train traffic was hampered by

delays across the northeast corridor with thousands of passengers waiting for hours. u.s. central command is investigating after navy fighter jet was shot down by friendly fire sunday. the uss gettysburg mistakenly fired on and hit that jet. the two navy pilot safely ejected over the red sea. for now, back to dateline. his goal? to get suspected serial killer larry hall to admit to the murder of 19-year-old tricia reitler and reveal the location of her body. if successful, jimmy would be released from a 10 year prison sentence. but even a hardened inmate like jimmy would not be prepared for the horrific story hall was about to share. here again is lester holt with the inside man. lester holt: by the fall of 1998, after several months in missouri's toughest federal prison, jimmy keene could have won a popularity contest.

he charmed everyone, just as beaumont knew he would. he even won over some convicts with his lending library of pornographic magazines. and he'd managed to placate the chin and the mob faction by day while circling his prey, suspected serial killer, larry hall, with one on one bull sessions at night. we just talked about a lot of normal things, hung out. made him feel like i was wanting to be his friend. lester holt: but it wasn't fast enough for keene who feared someone might recognize him and blow his cover. if you went by the fbi's technical terms, i was pretty much staying right on pace. but from my point of view of being in this place, it was starting to get very hard. lester holt: on the outside, the mission mastermind, larry beaumont, could only sit and wait for second hand news on how this crazy scheme of his was going. now were you pacing the floor waiting for updates during all this?

i don't know if i paced the floor, but i was eager to get updates. i had information that he was starting to trust him, they were talking, that kind of thing. lester holt: but beaumont had absolutely no idea that a breakthrough moment had arrived. it was a saturday night. keene and hall were in the prison's tv room, watching "america's most wanted" again. jimmy keene: and here comes this big prisoner, and he's a big, muscular, buff guy. and he walked over to the tv, and he turned the channel. and hall looks at me and he goes, real quietly, he mumbles under his breath, he says, hey, that's not right. i was watching that. i thought, you know what, this was a prime opportunity for me. lester holt: jimmy, a martial arts expert, who had continued working out in prison, was ready for this moment. he got up and changed the channel back. he jumped up and he's slobbering all over the place. you turn that channel again, i'll rip your damn head off. you don't touch that tv. he's going on all crazy stuff, and he turns the channel, and he sits back down. and i just looked at him and i turned the channel again.

and he jumped up, and he starts cussing at me, and then i finally threw a particular cuss word at him that i knew was going to set him off. and as soon as i did, he took a while haymaker swing at me. and i come up with an uppercut and nailed him. kicked him through three rows of chairs, and jumped on him, and i beat him to a pulp. lester holt: hall had a ringside view of saturday night's main event. afterwards, he staunchly defended jimmy as the retaliator, not the instigator, when prison officials interviewed eyewitnesses about the tv room brawl. you're larry hall's new hero. yeah, i became his new best friend and hero too. lester holt: jimmy could sense that his heroics had brought him even closer to hall. and now, he was ready to make a bold move. in the prison library, jimmy had figured out a strategy to draw hall out on tricia reitler. jimmy keene: i noticed he was reading his hometown newspaper. and that was really important eventually for me to start cracking into his psyche. lester holt: even though the goal was tricia's body,

jimmy decided to ask first about something already public knowledge-- hall's conviction in the jessie roach case. jimmy fit that his mother lived near wabash, and read about jessie's case and other stories involving hall. she gets that newspaper from that home town where you're from. and i said, all the newspaper stories say that you've killed multiple women. that was a big risk, though? it all was a big risk. and i said, larry, i don't care what you're in here for. but be honest with me, that's all. just tell me what happened, man i said, you know, i'm still going to be your friend no matter what. and i said, you know, i've had girls do me wrong in my life. i understand how girls can get under your skin and how they can be bothersome to you. lester holt: jimmy said he pressed hall about jessie roach. at last, hall began to open up, recalling that september day in 1993. he was driving down a country road and he seen her walking her bicycle. lester holt: hall then told jimmy exactly how he abducted and killed jessie.

you must have been revolted. oh god, lester, it was probably the hardest thing i've ever done in my life. to have to sit there and pretend to be his friend, to listen to this kind of stuff, and not just rip him apart. but i knew what the mission involved. i knew what was at stake for me. i knew what was at stake for the people's families that were still you trying to find their daughters. lester holt: a major transformation was taking place. jimmy was starting to care about more than just himself. and now, he was determined to squeeze the most crucial confession out of larry hall. and not just for himself, but for the family of tricia reitler. i started thinking, i don't know where this is still going to lead, how long this is going to take. but something's now happening. coming up, a disturbing discovery. has jimmy keene solved the mystery of the missing girls? i go, what are these things, anyway? he says, they watch over the dead, jimmy. he goes, they do. when dateline continues.

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lester holt: jimmy keene's five months of hell, five months making nice to a killer he despised, had finally paid off. hall had described in gruesome detail how he murdered jessie roach. i've opened that door and he's feeling that he can trust me enough now. lester holt: but jimmy felt he needed to wait a bit before going for the goal line. how did you approach tricia reitler?

i had to slowly keep prodding, because i didn't want him to think i was piling on. lester holt: so he carefully plotted his next move. days later, he thought the time was right. he tried that hometown newspaper ploy again. i said, you know, the newspaper say that you killed this girl from the college over here. i says, you know, what happened there? lester holt: jimmy couldn't be sure how hall would react. had he been too blunt, too direct? no, it was all clicking. according to jimmy, hall began to open up about tricia and said he drove his van right up to her that day he saw her outside school. he said that he tried to kiss her, and when he did, that she started fighting very violently. and he said she was a very strong girl, and she fought stronger than anybody had ever fought before. and did he admit it? he said that he had killed her and he knew he had done it again-- and these are his words-- that he knew he had done it again. and he said he went way out in the woods and he buried her way out in the woods. lester holt: hall gave a general location for tricia's body,

near a river in indiana. but jimmy needed more specific information. luckily, he seemed to stumble into it a few nights later when he spotted hall inside the prison woodshop, a restricted area. there's nobody at the door, no guards or anything. and i went in there. and as i came up from behind him, he had all these little different statues lined up. 10, 15 of them maybe. and i couldn't tell what they were at first. and as i got closer, i noticed he had a big map laid out. and he dove on that map and folded that thing up really fast, and slid it off to the side of the table. and i go, what are these things, anyway? he says-- there are these little falcons-- and he goes, they watch over the dead, jimmy. he goes, they do. and they looked like? a good sized chess piece. lester holt: jimmy had a strong feeling that hall's wood carved falcons and the map were journal keeping by a serial killer. that map had little red dots all over it of illinois, indiana, and wisconsin. you'd look down at this map and you

could see all of those little spots are burial spots where he's got somebody. lester holt: all those months of dangerous painstaking work had paid off. jimmy had cracked the case. mission accomplished. once you see the map, the falcons, you want to tell the fbi about it, right? i did. i went to the hotline i had for the fbi girl. i called. i get some type of a voice recording, it was after hours. lester holt: so jimmy left a message for his fbi contact to come get him, the map, and the falcons. his freedom and the answers to tricia's parents prayers we're now just hours away. i was elated. i felt i wrapped this up. you're expecting the troops to come marching in. expecting the troops to come marching in. and didn't quite work that way. lester holt: what he couldn't know was he's fbi contact didn't get his voicemail. and his one inside, contact the chief psychiatrist, was on vacation. then you got a little full of yourself, didn't you?

i did. i went back to my cell, i was really happy. i thought, you know what, 24 hours, i said they'll have me out of here. i've got what they need. this is it. and so i went across to his cell over there. lester holt: impulsively, jimmy decided he just couldn't leave prison without giving his fake friend a piece of his mind. the repulsiveness i felt about him throughout the whole time i had to stay be his friend, and the disdain and dislike i had for him-- that i thought it was good for me to unload on him and tell him what i really thought of him, and who he really was. i said, you know, so i'm going to be going tomorrow, larry. i said, you're a crazy killer. and i started calling him everything you could think of. lester holt: with that, jimmy returned to his cell, and waited to be released. you're going home the next day you think, and things take another turn. about 5:30 in the morning, i hear some little lady in a white doctor smock come walking in. lester holt: it was hall's psychologist, and she was furious that jimmy had

blasted her patient, turning him into an emotional wreck. she told the guards, grab him, take him, throw him in the hole. so they put me in the hole and they keep me in there. and i'm not really worried. i mean, yeah, so what. the fbi is going to be here. they told me 24 hours, they'll have me out of here. lester holt: but morning turned into afternoon into evening. and the cavalry still hadn't arrived. this was hard time at its hardest. you can't see if it's day or night because you're in the hole. but you can tell what time of the day or night it is by what meals come into the door slot. well, next thing you know, here's breakfast, lunch, and dinner. next thing you know, here's coming breakfast again. here's coming lunch. and i'm like, where are these guys? my thoughts were, they did me wrong. they got what they needed, they got the info, and they pulled the rug out from under me. lester holt: while jimmy was wondering where they were, beaumont was looking for him too. and we were like, where could he be. he's in a prison, for god's sake. lester holt: coming up. they lost you. yeah, they lost me.

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we were trying to find out, we're kind of getting frantic. lester holt: two weeks later, only after keene's psychiatrist contact return from vacation, did they finally find jimmy. by noon, the fbi was there, and she kept apologizing. she kept saying, i'm really sorry. you know, i mean, something happened with the message. lester holt: at last, investigators got to search the wood shop and hall's cell. but by then, the map and the falcons, items jimmy believe could lead to tricia, were gone. what were you thinking telling larry hall, you're out of here, and dressing him down? you know, people probably wouldn't understand the mounting pressure, that kettle's ready to boil over at any time, you know? and it just felt good to unload on the guy. i mean, the problem is, as i see it, you've unloaded on him, he knows you're against him. but nobody has that map. right. i'm disappointed i didn't wait another day or two at least. i should have waited a few more days. i wish i could have done more for him. but i did all i could do. and i feel in my being that i did all i could do.

lester holt: meantime, the people who would benefit the most from a successful mission, tricia's parents, only learned about the secret operation 10 years later in 2008, when the story came out in a "playboy" magazine article. the reitlers are thankful for jimmy's courage and the corroborating details he said he'd got from hall. but they're furious he blew his cover before finding their daughter. why would you have been so close and then give that up like you did? i try not to dwell on that at all because it eats at me, and it's very hard to deal with it. he was that close. lester holt: jessie roach's parents find small consolation in that jessie was the victim who tripped up hall. if something good could possibly come out of losing jessie, it's the fact that he's in prison, and he will never get released.

lester holt: hall remains in federal prison with no possibility of parole. he's since made more murder confessions to reporters and investigators. i sincerely believe that there are young girls out there somewhere who are alive today because larry hall is in prison. do you think he killed before? i think he killed before, and i think he would kill again. lester holt: jimmy did tell beaumont that hall had killed again. but there was no documentation. it was just jimmy's word. so to be sure, the prosecutor made him take a lie detector test, and jimmy passed with flying colors. he was telling us the truth. so i mean, bottom line is we have further information that larry was responsible for tricia. lester holt: a grateful beaumont decided to reward him with full credit for his brave undercover work, releasing him from prison, and scrubbing his criminal record clean. from his perspective, he expected to get nothing.

but from my perspective, i mean, of course, he had spent time in a loony bin with this guy, and gone through this whole process. lester holt: for 15 years, jimmy had been the only one to see those falcons that hall said watched over the dead. the problem is we never got them. i mean, they disappeared, so we don't know what happened to them. you've never seen the falcons? no. i'll show you a picture. that's one of the falcons. dateline took pictures of a falcon when we met larry hall's twin brother. he said larry carved the falcon in the wood shop at the springfield prison, and then mailed it to their mother. i showed a photo of that falcon to both beaumont and jimmy. what's it like for you to see that after all these years? well, it's definitely bizarre, but it's also reassuring to me, lester, and i'll tell you why. now these falcons backs everything i've said. this is exactly what it looked like. lester holt: after becoming a free man in 1999, jimmy got to spend five more years with a father he idolized

before big jim passed away. and he tried to make the most of his incredible opportunity. he sees the hall experience as something that gave him a second chance at life. lester holt: when we last met with jimmy, he'd done well in real estate, and co-written a book with author hillel levin, "in with the devil," which tells jimmy's compelling story of redemption. he said he also had several hollywood projects in the works, most notably the movie version of his book. but jimmy is especially proud that his book re-energized some cold case investigations, several targeting hall in indiana and wisconsin. at least one near a civil war re-enactment site. investigators dug up locations where hall spent time over the years, and found articles of women's clothing, and a belt modified with wooden handles,

all sent out for dna testing. but cold case detectives following fresh leads still haven't developed enough evidence to bring charges. i did a good deed and i did a lot of good things. and that's where i feel the redemption comes in. i've done something good for the things that i did wrong. that's all for this edition of dateline. i'm craig melvin. thank you for watching. . >> this sunday, finding common ground. >> something i hope we can do no matter who you voted for. to see each other not as adversaries, but as fellow americans. bring down the temperature. >> it's time to put the divisions of the past four years behind us. it's time to unite.