that night it was pitch dark. it was abandoned and it was secluded. it was his playground. this was the place we've been searching for. >> it was the still of the night when the killings started. >> i've been shot. me and my mother have been shot. >> you can feel and hear the fear in her voice. >> a single mother and her teenaged daughter ambushed in their bedrooms. >> here comes a monster into the house. >> i just broke down. i just couldn't imagine who would do this. >> then it happened again to another mother, another daughter. >> somebody's killing mothers and daughters. that's about as scary as it gets. >> scary as it gets. >> who was out there, and who would be next? >> something you would never imagine would happen.

>> the clues would lie here, an abandoned mansion. eerie, haunting. where was the the killer hiding? >> cold, calculating eyes. lifeless. >> he was almost a ghost. >> could they catch him? could they stop him? >> i get chills all over. i'm kind of on the edge of my seat. >> he truly thought he could outsmart us. >> i'm lester holt, and this is "dateline." here's dennis murphy with "the unusual suspects." >> reporter: consider for a moment that cozy word "home" and all it evokes -- warmth, family, shelter, security. got it? now reflect on what happens when those four walls are breached. when nightmares cross the window and kicks in the door. when a haven becomes a house of horrors. so how does that feel? just ask lloyd irvin. >> i'm laying on the couch.

i wake up, and there's two gunmen holding guns over me, pointing them, holding them down, you're being robbed. don't move. >> more than six years have passed since that night in august, 2008, here out the nation's capital in a nice neighborhood in prince george's county, maryland. but lloyd and viy irvin and their son, just 4 years old at the time, are still haunted by the image of the gunmen -- two masked intruders. >> talk about worst nightmares. this is it. >> yes. something you would never imagine would happen. >> what the robbers didn't count on was that lloyd is a nationally renowned martial arts expert. and when one of the gunmen walked way to scope out the rest of the house, lloyd was suddenly one on one with his accomplice. gunman's over here in the corner. >> he doesn't have any room to back up at all. i just go. i'm coming over, i got the gun, trying to get the cartridge out. once i get it out, it drops. it hit the ground. >> where does the intruder go? >> he ran out of the gun. he was low.

like, he has the gun, get out of here, he has the gun! >> by the time lloyd managed to reload the gun and gave chase, both home invaders escaped. >> i'm calling 911. my son's on top of me just shaking. not saying a word, not crying, just shaking. i often think, were they going to kill us that night? >> the irvin family wouldn't be the first or the last to ask that awful question. >> i'd like to report a robbery. armed robbery. >> someone broke into my house here. >> in the months that followed, the area was hit with a wave of home invasions. each time, two masked men. meticulous about not leaving fingerprints or evidence behind. the prince george's county police were baffled. the community understandably on edge. and then on january 26th, 2009, on a quiet street in upper marlboro, the county seat, anxiety turned to full-on bolt the doors panic. >> prince george's county 911. what is your emergency?

>> ma'am, i've been shot. me and my mother have been shot. i'm bleeding. >> where are you? >> it was a desperate plea for help from a dying girl. on the phone, 16-year-old student carissa lofton. >> please, slow down. what's the address? >> police rushed to the scene, but it was too late. they found carissa and her mom, karen, in their bedrooms, each killed execution style with a shot straight to the head. crimes quickly become statistics, but this just stands out, doesn't it? >> stands out. makes the hair on the back of your neck stand up also. >> veteran prince george's county homicide detective bernie nelson was in charge of the case. the first arriving officers told him they found the main door locked shut from the inside. the killer, they thought, had likely entered the house through an unlocked side window. >> this bedroom on the second floor that's facing us, that's where carissa was found.

>> detective nelson wondered, did the murders have anything to do with the plague of recent home invasion robberies? if so, why was nothing stolen from the house? >> her vehicle was still in the driveway. nothing appeared disturbed. >> investigators didn't find any useful forensic evidence, just six spent shell casings from the bullets that had kill karen and carissa fired from a glock 17 handgun. >> we did find out that just two doors down across the street, someone had seen a blue vehicle parked on the right side of the road and that, right now, at this point, that's all i have. >> reporter: so detective nelson set out to find out more about his victims. karen lofton turned out to be a devoted mother and nurse with no apparent enemies. she was divorced from carissa's father, kirkland, who now lived in atlanta. the daughter, carissa, was in private school, good grades, and still very attached to her father. >> carissa was a special girl for me because at a young age

she had open-heart surgery. and she bounced right back from it. >> reporter: kirkland said he had watched carissa blossom into a gregarious teenager, an aspiring model with a knack for selfies. >> i sang a song boy bob carlisle called "butterfly kisses." told a story of him and his daughter. she would just look up at me. she loved me singing that song to her. ♪ butterfly kisses >> she was my butterfly. that's what i called her. >> reporter: now kirkland's butterfly was dead. and detective nelson recruited some of pg's finest to help him solve the case, including detective anthony sharker. >> a mother hard working and daughter. both think that they're safely inside their home. >> reporter: here comes the guy out of your worst dreams. >> yep. here comes a monster into your house. >> reporter: and he's got a glock? >> it shocked us all. >> reporter: as the hunt for

this brutal killer went into full gear, detectives start, as they always do, with the usual suspects. >> since there was no rhyme or reason behind it that you can come up with, you have to look at family members. >> reporter: and one family member in particular -- carissa's 20-year-old brother, keon. he lived in the house, too, but he wasn't there when cops arrived. police spotted him near the crime scene several hours after the murders. could a son, a brother, have done such a monstrous thing? >> when we come back, the questions begin. >> would you you have hurt your mom and sister? >> no. one of the detectives blatantly said, "everybody in that room thinks it's you." >> was it? what happened next would launch a whole new wave of fears.

a mother and her daughter executed. detective bernie nelson had investigated hundreds of murders, had learned to keep the recurring images of death at arm's length. but this case was different. he was a father to a teenager around carissa lofton's age. >> ma'am, i've been shot. me and my mother have been shot. i'm bleeding to death. >> that poor little girl. in her bedroom, she has the gumption to get on the phone and call you. >> it hurts to listen to the 911 call because you can feel and hear the fear in her voice. >> even though nothing was taken, it seems clear the killer had broken into the house. in fact, the burglar alarm had gone off but it was disabled in under a minute. that put karen's son, keon lofton, at the top of the person of interests list. he lived in the house, he knew the code. police brought him in for questioning. >> does your mom set the alarm for the house? >> mm-hmm.

>> all the time? >> every day, every time. one of the detectives blatantly said, "everyone thinks it's you. you're the only one who had access to the pin code." >> would you have hurt your mom and sister? >> no. >> you wouldn't have hurt your mom and sister? >> no. i was upset. he's not going to say it was me. i didn't have anything to do with it. you can do whatever you have to do. it's not going to be me. >> keon told investigators he'd been spending the night at his fiancee's house when her mom woke him and told him she heard on the news that two women on his street had been murdered. >> i just ran out the house, my heart's racing. hopped in my car. i'm running lights. i'm still calling at the same time. and when i got the there, they asked my for my name and i was like, keon. the police officer looked into his radio and said, "yeah, we've got the son here." i just broke down. >> reporter: keon's alibi checked out. it wasn't him. investigators also interviewed kirkland, karen's ex-husband and carissa's father.

he, too, had an airtight alibi. he'd been in atlanta at the time of the murders. next on detective nelson's list was karen's former boyfriend, michael lacey. he'd refused to take a lie detector test, so police interviewed him three separate times. >> did all have keys to each other's house? >> absolutely not. >> you couldn't just walk over and walk in? >> would call. >> someone we had to rule out completely, and we did that. >> reporter: if you're thinking in your line of work the usual suspects, the usual suspects weren't going to figure in this one. >> not as far as immediate family. >> reporter: detectives nelson and shartner realized they had on their hands what homicide cops hate, a true mystery. the first 48 hours of the case, usually you get a break. there's something that says chase this. >> yes. normally you would get something within the first 48 hours. >> this thing was as baffling as it was cruel. >> exactly. it don't make any sense. >> reporter: then came march 16th, 2009, six weeks after the

lofton killings when two unsolved murders became four. it began with a report of a stolen nissan maxima. just a couple of blocks from where the loftons had been killed. >> what's the nature of your emergency? >> i left my house maybe an hour ago and had come back. my car is missing out of the carport. >> reporter: detective smartner was on call that night. >> she's on the phone with the call taker. she notices that her car comes zooming by from up here on the street and comes by her at a fast rate of speed. >> that's my car. okay, it just zoomed past me. wow. >> reporter: she sees it while she's on the phone with dispatch? here it comes, there it goes? >> absolutely. >> reporter: police swarmed the neighborhood hoping to nab the car thief. he was nowhere to be found. but police soon discovered the stolen car. captured here on a cruiser's dash camera, it was parked at a driveway of a vacant house

engulfed in flames. firefighters called to the scene to extinguish the fire made a grisly discovery -- two bodies burned beyond recognition. and the victims, another mother and her teenaged daughter. >> dental records confirm the identities of the two female bodies found monday in the trunk of this stolen car, 42-year-old dolores dewitt, and her daughter, 19-year-old ebony dewitt. >> she worked at a nursing home. and she loved taking care of the elderly population. i mean, she loved those people. and they loved her. >> reporter: patricia smith remembers her sister dolores as a mother and nurse who worked hard to provide a good life for her two daughters but always saved a little time for herself. >> she liked to go places. every year she would treat herself on vacation. she felt like she worked hard. she should play hard. >> reporter: and ebony, she was the livewire at family get-togethers. >> just would make the party liven, just act crazy until the end of the day. i mean, she loved life.

>> reporter: the last person known to have seen ebony alive was her boyfriend. he told detectives that the previous night they'd had a late dinner, she was wearing her favorite blue sweater. then he drove her home, watched her go inside her house. the killer may have been waiting, and now, when police once again made no arrests within 48 hours of the murders, waiting, too, was a devastated patricia. >> i started going back to my sister's house late at night. i would go and sit in the yard. just hoping that he would come back. i would sit there with the knife in my hand. and i would hold it real tight in case he came up on me or something because it would be him or me. either him or me. i told the detectives what i did. >> she couldn't sit still and do nothing. she wanted to be involved in the investigation from day one. she would actually go door to door in the neighborhood and

talk to neighbors, tried to ask them questions. but i had to repeatedly explain to her that we can't have her interrupting our case. >> reporter: she's a thorn in your side. >> she is, but i understood because if my sister were killed, it would be hard for me to sit still too. >> reporter: so detective shartner made patricia a promise. >> we were sitting in the car. and i remember crying and crying and crying. he promised me, he said, "i'm going get him if it's the last thing i do." he said, "i'm going to get him." >> reporter: to do that, detective shartner and nelson had to confront a terrifying question. you have two murdered mother/daughters across the fence virtually. same neighborhood. you're thinking, are these things related, right? >> you have to think that. and if they are related, you have a serial murderer on your hands and you don't know when he's going to hit next and you don't know who he's going to hit next. coming up -- >> the fear that spread was absolutely amazing.

>> a neighborhood on edge. police under pressure, and the question everyone feared -- would there be another victim? >> it was wide open. we had nothing. that's when it gets scary. >> when "dateline" continues. hey foster farms! looks like you left these two west coast birds behind! foster farm's chicken's california grown. you guys aren't from here. wrong! we love yoga and sunshine and stuff. well foster farm's chicken has no added hormones. well i wish you didn't have any added negativity! ha! high five! yeah! he's not going far. they're local. introducing fresh and natural chicken. california grown with no added hormones. from foster farms. simply better.

prince george's homicide detectives bernie nelson and tony shartner hope their collective experience would help crack two of the most horrific murder cases they'd ever encountered. when you back up and look at what you've got, the scary fact is somebody's killing mothers and daughters, right? that's the commonality. >> yes. and within close proximity of where the dewitts were found burned in the vehicle, it was just two blocks away from where the loftons were shot in their house. >> reporter: the detectives suspected they were dealing with the same murderer in both cases, especially when they realized dolores dewitt was a single mom and a nurse just like karen lofton. but first they exhausted the usual suspects. dolores had an ex-husband and an ex-girlfriend, but both had solid alibis. >> had given them polygraph tests. they passed. we did background checks on them. we found out where they were. there was nothing that would lead us to say that they were involved. >> reporter: as in the lofton case, when detectives search the dewitts' home, they found no

sign of a forced entry, just an unlocked side window. and inside the house, once again, no forensic evidence. but a different pattern -- the killer had taken his victims with him. >> we don't know if they were killed inside the house and transported away or transported away and killed elsewhere. >> reporter: the burned-out nissan maxima that carried the bodies didn't yield any significant clues either. the fire had destroyed everything but a tiny piece of jeans on dolores' body. and attached to the jeans, some leaves foliage experts identified as coming from a beech tree. odd because there were no trees like that in the neighborhood. and the mystery only deepened when the autopsy results came back. >> ebony and dolores were actually killed 24 hours prior to them being burned in the car. that was another hiccup in the case. where were these two bodies kept for a full day? >> reporter: it seemed the dewitts' killer took immense risk to get rid of the bodies.

>> you're talking about taking two women out of their house and transporting them to another location, and then stealing a car, putting those dead bodies in the car, driving past the house that you just stole the car from, and then parking it in a driveway of a vacant house, then setting that car on fire and walking away. >> reporter: and the autopsy also revealed that dolores and ebony were strangled, not shot as the loftons had been. it was a puzzle. were they dealing with a serial killer or not? did you think one guy was responsible for both these crimes? >> my mind would go back and forth. one day i would -- it was all in that this is the same person. the next day, i thought it wasn't, because both crimes were so different. >> reporter: then finally, the detectives caught a break. they learned that a month before the dewitt murders, the owner of the stolen nissan maxima had been the victim of a break-in. she reported it but at the time told police nothing had been taken.

now she noticed her spare set of car keys was missing. so, tony, i understand your detective's logic goes something like this -- if i can find the person who broke in, who stole the key, who used the strong transport the bodies, i'm getting close to my killer. >> exactly. certainly would give me direction where maybe that person can direct me to the killer. >> reporter: 200 police officers blanketed the area and brought in more than 80 people for questioning, all to no avail. for many prince george's county residents, like home invasion victims vicky and lloyd irvin, that meant only one thing -- panic. >> it was crazy. i couldn't sleep at night. any sound -- i had alarms put up throughout the entire house. plus, we have the dog. [ barking ] >> and bars on the windows. >> yes. >> the house was turned into ft. knox. a barking crazy dog who claws at the windows if he hears the doorbell ring. there was no peace in the house. i was like, you have to turn some of this stuff down. i can't live like this. he's like, i don't care.

this is going save our life. just the fear that spread was absolutely amazing. >> reporter: by july, 2009, four months after the dewitt murders and six months after the lofton murders, detectives were stumped. kirkland grew frustrated. >> they went to karen and carissa's house and started combing back fields for evidence there. so i think that the investigation started off bad because they were so sure that the usual suspects was the suspects. >> we kept calling them, and they wasn't giving us no answers. so that kind of pissed me off because i felt like we deserved to know something. >> it was wide open. we had nothing. >> reporter: you were out of your investigative playbook. >> that's when it gets scary. >> reporter: the detective had made a promise to patricia he will take down her sister's killer. would that turn out now to be an empty promise? at this point what he needed was luck, and luck was about to come his way from the most unexpected

source. coming up -- >> he would only whisper, he would actually whisper in my ear. >> an unassuming neighbor comes forward with some unbelievable information. >> at that point, we realized that our investigation took a drastic turn.

prince george's county detectives tony shartner and bernie nelson theorized the home burglar who stole a spare key to a nissan maxima might lead them to a serial killer, but how to find him? >> we chased down all those leads, and it took us several weeks, and we came up with nothing. >> reporter: then in july, 2009, shartner got an unexpected tip. federal agents from the atf, the bureau of alcohol, tobacco and firearms, had arrested two men for selling stolen weapons. they suspected one of them had also been involved in several burglaries in the area. his name was jason scott. >> jason scott lived two, three blocks away from the dewitts' house, so obviously that's somebody that i want to go talk to. >> reporter: the detective and the thief met in a police station holding room. the subject, who was quick to

deny he had anything to do with any of the burglaries, looked to shartner like a pipsqueak. >> he was a small guy. he was meek. his voice was very low. he wouldn't speak to me as you and i are speaking. he would only whisper. he would actually come up and actually whisper in my ear. >> reporter: did you think, tony, at this point, i've got a suspect here? >> no. >> reporter: atf agents john cooney and dave cheplack led the federal investigation into the weapons threat. they, too, were having a tough time trying to read jason scott. >> we're pursuing the most violent criminals in the united states, and for lack of a better word, this guy wasn't a thug. >> reporter: in fact, jason turned out to be a college graduate and a valued employee at ups. >> we did a background check on him, and really he had no criminal history. >> reporter: jason and his accomplice were charged with weapons theft and possession. but given that neither had a criminal record, a judge released them pending trial. >> she basically had to make a decision, all right, you're not a flight risk, and you're not a

danger to the community. so both of them were released to home monitoring. >> reporter: so they could come and go. the court is telling them, go and sin no more, don't be stupid, don't be a bad guy? >> yes. >> reporter: but the atf agents weren't about to let jason scott walk away quite so easily. they suspected he had other co-conspirators on the weapons theft, and instincts suggested he just might be the type of petty criminal happy p to throw others under the bus in exchange for a lenient deal. the detective offered him a proper session, sometimes called king for a day. in monopoly it's known as a get out of jail free card. it's an agreement between the prosecutor and suspect that says essentially you tell us everything you know, and we'll go easy on you. and the stuff that i spilled out, you will not come after me, that's the agreement? >> if we can't prove that any other way besides him telling us, then there's nothing you can do. you can't use his statements against him when that statement is given in the proper setting. >> reporter: the agents had been

on the job for a long time, but what happened next stunned even them. >> so we come into the room to conduct the proper session with jason scott. myself and jason are on this side of the table. jason and his defense attorney are sitting across from us. we see that jason has three pieces of paper in front of him on the table. dave and i look at the papers and see about 40 different addresses. suddenly, jason admits to breaking into all these houses. not only that, nine of the houses, he tells us he breaks into, wakes people up, points guns at their heads and robs them of their valuables. at that point we realize we're not just dealing with a guy selling and stealing guns. our investigation just took a drastic turn. >> reporter: jason had rocked the federal agents off their script. the king for a day deal was about copping to the firearms charge. and here he was telling them instead that he and his accomplice, marcus hunter, made a living by pointing guns at so many peoples' heads including during that botched invasion of the irvin family.

but he's cut his deal, john. you can't go after him on the burglaries, home invasions. >> at that point, you're correct. >> reporter: he's home. he's off scot-free. >> home free. >> reporter: even better for jason, he believed his accomplice, marcus hunter, alone, would be the one to take the fall for the crime spree. >> he figures if i'm the one to testify against marcus, that will be the opportunity to lessen his sentence. >> reporter: smart, cunning. how good was this guy? >> he certainly had a plan and an idea of what he was trying to get away with. it was a real-life cat-and-mouse game for him. >> reporter: back at the county, detective shartner was floored when he heard from a colleague this the pipsqueak he'd interviewed and dismissed the week before had fessed up to a majority of the unsolved home invasions and burglaries in well-to-do neighborhoods of prince george's county, including one his colleague had been be investigating. >> i thought, good for you. you got your case closed out, but i'm still here with four dead women that we haven't solved. i said, out of curiosity, can you give me that list?

>> reporter: when the detective plotted the addresses jason had pushed across the table on to a map, he couldn't believe the picture that emerged. is this an "aha" moment in your investigation? >> this is the "aha" moment. this is our first break in the case. coming up -- >> we don't know if we have our guy, but we certainly have now something to investigate. >> the investigation was about to lead them here, something called the spooky house. and a federal officer on this case would soon be spooked himself. >> actually grabbed my gun and proceeded to tactically clear my house. that's how concerned i was. he's that dangerous of a guy. >> when "dateline" continues.

this is ground zero. this is where i responded to at this location, and this is where the dewitts were found. >> reporter: thinking he'd made the deal of a lifetime, mild, meek jason scott had confessed to a wave of home invasions and burglaries in prince george's county, maryland. but by doing so, he had unwittingly provided homicide investigators with the first real lead in the lofton and dewitt murder investigations. what happens up here as you continue to go up? what are the other dots? >> these other various dots on the map, locations where jason scott admitted to breaking into

the houses here on woodlawn. >> reporter: here's what the detective found strange -- jason had admitted to every unsolved burglary on the block. all but one -- the house from where the nissan's spare keys were stolen. >> for me, the most important part of this puzzle was to find out who broke into this house right here. >> reporter: in the interrogation, he did not give you that address? >> he did not. >> reporter: an anomaly, shartner wondered? or did jason know just how important the car keys were and deliberately keep that house off his list? >> we don't see guys that break into houses and steal a tv, then morph into a serial killer. we don't know if we have our guy, but we certainly have now something to investigate. >> reporter: detective shartner and nelson teamed up with atf agents cheplack and cooney to create a task force to solve the riddle of jason scott. when you guys talked to friends and family trying to figure out who he was, did anybody tell you he was a nice guy? i can't believe you've got him in the frame for this? >> nobody had anything like that to say about him. as a matter of fact, most people knew nothing about him. he was almost a ghost.

>> reporter: a ghost, indeed. when investigators examined items seized at jason's home, they found this -- disturbing videos he apparently shot as he snuck around the neighborhood. turns out jason scott was as scary a peeping tom as investigators had ever seen. >> video of someone walking through the woods videotaping people through their homes in various states of dress and undress. getting ready for work or getting ready to go to bed. >> reporter: this is deeply creepy stuff. >> absolutely. >> reporter: the person who knew him best was marcus hunter, the accomplice first arrested with jason scott. but marcus wasn't talking. investigators wondered, was he afraid of jason? another former co-conspirator was telling investigators jason was no one to cross. >> he's sensitive. you have to watch how you talk to him. >> these guys would say, if i got into a fight, jason wouldn't fight back, but two weeks later

he would be the type of guy to come back and burn my house down. >> he was crazy. >> reporter: three weeks after his king for a day deal, jason scott was still walking the streets. and investigators knew enough about him to worry for their own safety. >> his m.o. was he would specifically go and cut the power to these homes. so one night sleeping, i kind of become aware that all of a sudden the power is off in my house. knowing that jason knew my name and thinking that he could figure out where i lived, i actually grabbed my gun and proceeded to tactically clear my house just to make sure that he wasn't the reason for the power being out. as i work my way through the house and into the kitchen, i finally come up and i notice that in the back yard the entire neighborhood is dark. at that point in time, i kind of take a sigh of relief and i realize it's not him. but that's how concerned i was. he's that dangerous of a guy

that i recognize he needed to be in jail. >> reporter: if jason scott was smart, the task force simply had to be smarter. and investigators noticed jason didn't seem to understand an important legal nuance -- his proffer didn't guarantee him complete immunity. the cops could not use his own words against him, but they could use the words of others. so when investigators found that other accomplice of jason's, they grilled him. >> do you know about breaking into the house and just taking car keys? >> he's told a couple that he might go in and take keys in case he needs to have the car. >> reporter: the details eerily mirrored what happened in the dewitt murders. >> he likes to steal car keys, spare keys. and he likes to come back later and get that car. that was the first -- >> reporter: first indication of the nissan? >> first. he liked to park cars in vacant houses, preferably houses that were for sale. >> reporter: again the torched car with the bodies --

>> was a vacant house that was for sale. >> reporter: detective nelson nailed down several connections between jason scott and the first mother/daughter murders, the loftons. the most important of those, jason's car, a dark blue toyota camry. it matched the descriptions of one of the cars that the neighbor had seen. that could well have been the vehicle the neighbor saw the night of the killing. >> yes. >> reporter: then investigators discovered another sickening piece of evidence, a video jason made of one of the victims of his home invasions, a mother and her teenage daughter. >> brought her into her bedroom, and set up a video camera. in the process of setting up the video camera in which he was going film himself sexually assaulting her, the camera just happened to pan right by his face. and the screen shot showed us this. >> reporter: wow. >> this is what a lot of jason's victims saw. it's cold, calculating eyes. lifeless. >> reporter: investigators were

shocked. even more so when they dug up the old police report and noticed what the perpetrator they now knew to be jason had blurted out to the mother and daughter just before he left. >> okay, here it is. he said he didn't want to hurt us, but he said he was supposed to kill us. >> reporter: yet all this evidence was purely circumstantial, not enough to charge, let alone convict jason of murder. but that was about to change. and it had to do with the one case police had plenty of evidence for -- the weapons theft. when the atf agents talked to jason about it, he mentioned the spooky house. some kind of an abandoned old property off the beaten path in upper marlboro. the place where he said he and his accomplices used to go to divvy up the loot. detective shartner had a spooky feeling that they brought more than guns there. >> we're still trying to find the place or house or wherever where the dewitts were stored or

kept for those 20-some-odd hours. >> reporter: the spooky house, whatever it is, could be the place? >> absolutely. >> reporter: and according to jason's proffer, if the statements led to new evidence, the evidence could be used to prosecute him. >> my first thought and impressions were that this is going to be like an old, rickety house, maybe falling apart. >> reporter: doesn't feel like we're headed to spooky house, guys. >> no. it wasn't until we came here that we realized there was a long driveway here that maybe made sense. >> reporter: there it is, huh? the spooky house was a georgian mansion up for sale. and, like the property where the nissan was set on fire, vacant. what a hideaway to do whatever you want to do away from prying eyes. >> absolutely. at the night, this is absolutely pitch dark. this is just a playground that jason scott had. >> reporter: the task force called in the forensic team. >> walked down here through

these rocks here. that's when i first initially saw the sweater which was actually right down here in the rocks. >> reporter: it was the charred remains of a blue sweater. the kind ebony dewitt had worn the last time she'd been seen alive. >> and once we saw that, we said, this is it. this is finally something. and you're talking about a high-five moment. we looked a bit further down these rocks here, and scattered within these leaves over here were jean pieces. >> reporter: jeans that seemed to match the jean fragments recovered from dolores dewitt's body. leaves covered the ground there, and the task force wondered whether they were beech tree leaves, the type that were found attached to dolores' jeans. detective shartner brought an expert to the spooky house to identify the foliage. >> pulled up here and he said, this is the jackpot of beech trees. >> ebony and her mom were here, no question? >> without a doubt.

>> reporter: but to arrest jason, investigators needed more. in the meantime, they eliminated his accomplice as a murder suspect, so they hit him up again, hinting jason is talking and if you don't, you'll be the one to take the fall. that did it. marcus hunter finally agreed to cooperate. right away, he dropped a bombshell about jason. >> the specter of him becoming a monster grows with each and every stone that we overturn. coming up -- >> i think he truly thought he could outsmart us. >> could he? what would it take to put jason scott behind bars? and -- >> let me tell you something that will probably freak you out. >> one more chilling revelation for the irvin family. >> are you serious?

>> reporter: almost six weeks after jason scott walked out of the prosecutor's office with a potential stay-out-of-jail deal in hand, the task force persuaded jason's accomplice, marcus hunter, to cooperate. the king for day was about to be dethroned. >> marcus tells us about a month prior to the dewitts being killed he and jason are running through the back yard because they had just done a job. and jason stops and looks in to the dewitts' house. he notices ebony, and he starts to stare. marcus gets uncomfortable and says, "hey, we can't stay here all night. you need to go." >> reporter: much more damaging, the accomplice told the task force that after yet another robbery and approximately an hour before dolores and ebony were killed, he'd given jason a ride to his car, parked just a

block or so from the dewitts. and the accomplice had more. >> he said that there was at one point, and it was during the time that the loftons were murdered that he had seen jason scott for a short time frame with a glock 17. >> reporter: a glock 17, the very weapon used to murder karen and carissa. >> i had one of our investigators try to find out who purchased glock 17s over the last two years and then contact those people and find out if they can account for their handgun. and he found out that a home was broken into 13 days before the loftons were killed, and during that break-in, their glock 17 handgun was stolen. >> reporter: and here is where detective nelson got lucky -- the state of maryland requires handguns to be test-fired before they're sold to help identify or trace the weapon should it later be used in a crime. >> we immediately took out the

shell casings and had them compared to the known shell casing from that known handgun. and during that testing, they were able to verify that all six shell casings came from that one particular glock 17. that was the weapon that was used to kill both of my victims. >> once we found out where the murder weapon came from that was used to kill the loftons, we needed to find out if jason scott ever had that gun in his hands. so we asked him accomplice, marcus hunter, if they ever broke into a house in this one particular neighborhood. he said they did. it was only one house. we never told him which one it was. and he took us directly to it. the house that the glock was stolen from that killed the loftons. as far that handgun goes, i think that was the nail in jason's coffin. we know that he stole that weapon. >> reporter: did that solve the lofton murders? >> it got us close as we were going to get. >> reporter: detective shartner and nelson arrested jason scott

at his home on september 2nd, 2009. >> i distinctly remember telling him, "jason, take a look at your house. this is the the last time you'll see it." >> he didn't even have a response. he just gave some type of noise, smacking his lips, as if, "i'll be back." >> i think he truly thought he'll get out of it. fortunately, between bernie and i and the two agents from the atf, we outsmarted him. >> reporter: and personally, the takedown of jason scott made the detective a promise-keeper. >> he said, "i'm going to get him. if it's the last thing i do." he said, "i'm going to get him." and he got him. >> reporter: in exchange for his cooperation, marcus hunter got a reduced seven-year sentence for weapons possession. it would be another three years before the atf and county police analyzed all the evidence against jason scott. when all was said and done, he was sentenced to 185 years in

prison. >> one of the things that the judge said, and i'll never forget this, you're not even a crime wave, you're a tsunami of crime. >> satisfaction to take down a guy like this? >> extreme. >> that was the proudest moment of my career. >> reporter: but jason did cut one final deal. in exchange for acknowledging that prosecutors had enough evidence to convict him for the dewitt murders, the state agreed ton prosecute him for the loftons, and that didn't sit well with the lofton family. they had their doubts about whether jason killed karen and carissa, whether the circumstantial evidence really proved he had pulled the trigger. >> we wanted a trial in this case because we wanted to see him on the stands admit what he did and be charged and convicted and sentenced for murder. it would have brought answers. it would have gave us a reason to stop looking. >> reporter: what do you say to someone like kirkland lofton, who wants to have their day in court against this guy? >> i fully understand kirkland lofton's position and the lofton family. i feel for them.

i want them to have their day in court. i went ahead and typed up a statement of charges to charge jason scott. i just couldn't get the blessing from the state's attorney's office to go forward with it. >> reporter: but you would say to him, jason scott is the killer? >> i would say to him that jason scott is the killer. he's who took carissa away from him. but the bottom line is we know that jason is gone forever. he only has one life to give. we can't punish him any more than what he's already being punished. >> reporter: the serial killer, the master robber and burglar, will likely die behind bars. the neighborhoods he terrorized are safe again. but under some roofs, there's been damage to that concept of home as a sanctuary. take vicky and lloyd irvin. they've kept their burglar bars, their home alarm system. they didn't know how much they needed that stuff until we filled them in. let me tell you something that

will probably freak you out, and this gcomes from guy number two in your house. he said after the home invasion, they came back. >> are you serious? >> reporter: he wanted another round. they parked in front of your place, did a little surveillance, scoped it out. and jason scott wanted to come back in and even the score. >> i didn't know that. that's scary. >> reporter: it could have been your picture on the 11:00 news. >> that's right. how does one person cause so much damage and so much hurt and so much loss to so many people? it still blows my mind. that's all for now. i'm lester holt. thanks for joining us. next at 11:00, traffic head aches this holiday weekend. how to get around all the shut downs and missing for 42 days and found safe. the amazing story for the search for this man's best but foster farms simply raised chicken is 100 percent natural with no antibiotics.

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