i would lay in bed with my imagination and i would play out possibilities of what happened that night. i thought about how scared she must have been. it was hard to go to sleep some nights. >> a young woman living on her own murdered in the middle of the night. >> she was at her most vulnerable, alone and in bed. >> a crime that jolted a sleepy seaside community. a killer walking among them. >> i don't think it really sets in that we're all a little more in danger at that point. >> young, fun and pretty, corey had plenty of admirers. had one of them liked her too much?

a strange co-worker. >> admit it. my god. >> i was. i was obsessed. >> that's scary stuff right there. >> exactly. >> an adoring friend. >> her statements about how much she loved corey piqued our interest. >> and a young man who made some people very uncomfortable. a gallery of potential suspects, piles of evidence, but the truth would only be revealed by a tiny telltale clue. >> did everyone's jaws drop? >> my eyes filled up with tears. i couldn't believe it. >> i'm lester holt, and this is "dateline." here's andrea canning with "rear window." >> reporter: maybe it was the hypnotic hum of night coming to life. then again, maybe it was just the booze or the talk of some easy money. >> we're all just sitting there

having a couple beers fishing, relaxing and enjoying. >> reporter: somehow three friends kicking back on a lakeside dock found their evening sliding into the past, a brutal unsolved murder, an investigation stalled, an old name resurrected. as they remembered, their eyes grew wide. what is your gut telling you as you're sitting on that dock? >> we're probably on to something. >> reporter: and someone who would prefer to stay hidden. strange how the night can shine a light into the darkest places. like so many others, corey parker came to florida for the waves and weather, but she stayed for the people. like amy lavin. do you remember the first time you met corey parker? >> i do. >> reporter: corey, a young 20-something when she and amy became fast friends. >> we were at pete's bar on the beach. and we were actually in the

bathroom waiting in line. >> reporter: and what did you say to her? >> i think she started the conversation and just said, hey, i see you around all the time. you know, we should hang out. i said all right. >> reporter: did you two get into a lot of trouble? >> we didn't get caught doing things or we probably would have. >> reporter: corey was a transplant from upstate new york, towering and sweet like a sugar maple. >> corey was 5'11", and she would wear heels. so she was so tall, and i'm very short. i think every time she walk into a room, people looked at her and she was so beautiful. >> reporter: did she kind of look like a model being 5'11"? >> she could definitely model. >> reporter: instead she chose a humbler route, taking classes at a local college and waiting tables at ragtime tavern at jacksonville beach. amy says that was pure corey. did she like being a waitress? >> she loved pitship could talk to people and superfriendly. >> reporter: she was a people

loved corey, both were fiercely independent. corey, in particular, had just moved into her own apartment. >> this is absolutely an exciting moment for her, moving into this place because she was finally being able to do it on her own. >> reporter: this was a big kind of independence day for her then? >> it was a really big deal, yeah. >> i was excited that somebody else was going to be moving in that i might be able to talk with. >> reporter: ashley burk remembers corey's move-in day that september of 1998. ashley, then 18, lived next door with her mom and older brother joe. core, at 25, seemed like a big sister. >> we would sit outside. she would do her laundry, we'd have a little glass and wine and just talk. >> reporter: about work, school and corey's new boyfriend, a young man she'd only met three weeks earlier at one of her favorite late night haunts, the ritz. ashley sensed her neighbor was falling in love. >> it started getting pretty

i really feel like that. >> reporter: but there was something troubling, too. corey was feeling uneasy about her ground floor apartment. her bedroom and front door were across from another building. >> it was someone else in our building that saw a peeping tom, and saw that someone was looking into her windows. >> reporter: ashley says for that reason corey preferred hanging out in the back of the apartment in the kitchen. that's where they were the day before thanksgiving. corey was making dessert to bring to a friend's house for the next day's feast. >> so we drank a beer, started making some pies, and she was telling me about thanksgiving. she was telling me where she was going. and i didn't even know she could bake. >> reporter: when she finished, corey went out for the evening. amy, who had left town for thanksgiving, remembers being tempted to stick around jacksonville beach so she could party with her best friend.

but i opted to go to my mom's the night before and spend the night. >> reporter: photos from that night show corey inside her hangout, the ritz. she's seen looking back at the camera, one of the women there was a new friend. her name was tiffany zienta. >> we were young and all in college and felt that, you know, we just would all go hang out. >> reporter: you and corey went out a lot? >> we did. >> reporter: your relationship kept getting closer and closer? >> yes. on my part, i guess. i can't answer for corey. but yeah. from my vantage point. >> reporter: that night, tiffany says, corey, usually the bubblyist in the room had fizzled out early, 1:30 a.m. >> we left at the same time. >> reporter: how do you part ways? >> she got in her car and i got a ride from a co-worker. >> reporter: she says corey promised to stop by her place the next day, but thanksgiving came and corey was a no-show.

>> i didn't think much about it. but i did tell my mom that i was a little bummed out that she didn't call and didn't come by. >> reporter: was that like corey to not call -- >> not at all. >> reporter: is she the type that would say, hey, i'm going to bow out for tonight? >> correct. >> reporter: it wasn't until the day after thanksgiving, black friday, that someone finally noticed corey missing. she didn't show up for her morning shift at the restaurant. no one had heard from her in more than a day. >> so one of the cooks, had was a friend of ours, said i'll go check on her, because she didn't live far from where she worked. >> reporter: the man returned to the restaurant to report that corey hadn't answered her door. alarmed, the manager sent him back. >> he walked around the back of her apartment, and her blinds were closed in the back, her bedroom, but there was a little opening. and he could see her foot and there was blood on her foot. >> reporter: the co-worker immediately raced back to work in a panic. police we

corey parker had just been found. >> what had happened to corey? inside her apartment, the first chilling clues. >> you could tell that she had fought for her life. >> and why detectives are sure her attacker was no stranger. >> that speaks to some sort of a relationship. why be in the kitchen when you can be in the moment? olive garden now offers catering delivery. we make the food and deliver it to your door...

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it was just before noon on black friday. ashley bird woke up to banging

>> they're like, are you corey parker. i said, no, i'm not. i said, i point at the kind of like the window next to me, which was her house. and i said, she lives right there. >> moments later, officers were in corey's apartment. >> and i heard what, you know, they had said there she is. and i just fell to my knees. >> reporter: 25-year-old corey parker was dead. it was clear she'd been murdered. investigators called state attorney angela corey, then an assistant prosecutor. >> the police were all there when i arrived, and so they walked me through the scene. >> reporter: how hard was it seeing corey parker in that way? >> it was brutal because you could tell that she had fought for her life. you could tell that she was at her most vulnerable. alone and in bed and that she had been, you know, brutally and viciously stabbed in the middle of the night.

hundred times. this was a sick individual who did this. >> very, very. >> reporter: it didn't take long for word of corey's death to spread from the tiny apartment. amy lavin, still visiting her mother out of town, got a call from corey's boyfriend. >> he was crying. and he said, did you hear what's going on? i'm so confused. i said no. what's wrong? everything's fine. and he said, corey, there's something wrong with corey. somebody found her in blood. and i said, no! no, she's fine. i talked to her yesterday. everything's fine. >> reporter: still, she drove back to jacksonville beach, straight to the police station, just to make sure. did it finally register at the police station eventually? >> i went into a room with a detective. they did confirm that she was found in her home dead. i kept thinking, something happened to her heart. i don't know why i kept going back to that in my mind. i don't know why. >> r

nights earlier, was finishing her bartender shift when a customer broke the news to her. >> i had this feeling kind of wash over me. and called amy. and asked her if it was true. and she said it was. >> reporter: detectives on the scene, meanwhile, were busy talking to corey's neighbors and sizing up the layout and location of her apartment. that in itself was a red flag. >> my first time here at first glance doesn't necessarily feel like the safest situation for a young woman living in this ground floor apartment. >> right. there's a lot of transient traffic that comes through here. the beach is three blocks from here. >> reporter: detectives billy carlyle and katie kingston, both now retired, worked the case. >> she was a beautiful woman. and whenever she would walk to and from her apartment, i'm sure there were a lot of guys that were looking at her. >> reporter: there's a lot of apartments around here.

you must have had to do a lot of canvassing. >> we did. we had to talk to every one of those people, document it all. >> there's a lot of partying going on at the beach. you have people wandering up and down the streets here at 2:00, 3:00 in the morning sometimes. so you know, yeah, that's a concern. >> reporter: neighbors told police there had lately been a peeping tom creeping around the area. so it was possible she was killed by a complete stranger who had broken into her apartment. >> it looked like the suspect had put his hand on the kitchen counter right there at the lip of the sink in order to lift himself up on the cabinet to be able to extricate himself from the window. >> you could see what almost looked like hand prints coming like they lowered themself out the window. and those were in blood. >> reporter: it was corey's blood. traces of her murder left by the killer. but the idea that this was a random killing didn't sit well with detective

was your gut telling you that this was someone she knew? >> yes. yes. >> reporter: what was it? why were you thinking that? >> well, because of the extensive stab wounds. she was stabbed 101 times. and that speaks to some sort of a relationship. >> reporter: they hoped to find traces of her killer in the mess left behind. there was plenty of evidence to test. fingerprints on wineglasses and cigarette lighters, hair and blood everywhere. >> you just never know what's valuable. so you try and photograph everything, then you try and examine everything that you can, that you think is potentially involved in it. >> reporter: and every one. the first person they needed to talk to was the new man in corey's life. you all wanted to talk to the boyfriend, a logical place to start. any red flags there with him? >> no. we determined through plane flight tickets that he was out of town at the time. he wasn't even here in jacksonville beach. >> reporter: was it a solid

>> reporter: but these were early days in the investigation, and there were many people in corey's world for police to rule in or out including a man who lived right next door. ashl ashley burg's brother. police had a reason to talk to him. >> coming up -- >> did he have a solid alibi? >> no. >> questions about a neighbor's whereabouts, and then suspicions about a co-worker's feelings for corey. >> did she know you were obsessed with her? >> i was. i was obsessed.

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this was low-key jacksonville beach, florida, where the main concern of the day was how high the waves were riding. a young, single woman attacked in the night in her bed just didn't happen here. >> i think this case illustrates every woman's nightmare that as hard as corey parker tried to be safe and she had all her doors locked, she still was the most vulnerable in the sanctity of her own home. >> women who lived alone were scared. >> reporter: melissa nelson, then an assistant prosecutor who joined the case, recalls the fear. >> neighbors were scared, people she worked with were alarmed. it was a very scary time for that community. >> reporter: tiffany zienta raised in jacksonville beach couldn't believe this had happened to someone she knew. >> i mean, they kept calling it the bloodiest crime scene in jacksonville beach in 25 years. that's not really comforting to feel or to hear. >> reporter: ashley burg was

reason. detectives thought her brother joe had been too vague about where he'd been in the hours surrounding corey's death. did he have a solid alibi? >> not really, no. >> reporter: what was he doing? >> well, you know, he was at the apartment just hanging around. and he comes and goes. so we couldn't really establish a solid alibi at the time of the crime. >> reporter: their interest grew when they found a hair on a sock in corey's bedroom. the hair looked like it could have come from joe. >> i know we did a microscopic comparison. and that the microscopic comparison developed that likeness. >> reporter: the test they used back then wasn't definitive, but it was enough to make police suspicious and for joe to worry. >> so they would ask, well, why is your hair on her sock. he couldn't answer that. he was petrified. petrified. he didn't know, you know, what they were going to do next. >> reporter: what police did was take a sampl j

testing and press on. meanwhile, there was another young man they were interested in. a dishwasher named eric eely. >> he was a co-worker that worked with corey at ragtime tavern. >> reporter: and everyone knew he really liked corey. >> had come on to her on multiple occasions and had also done that to several of the other waitresses up there. they just thought he was a creepy guy. >> reporter: who had grown stranger by the day. police found out he'd been pestering corey to have thanksgiving dinner with him alone. each time she turned him down. detectives brought the young man in for questioning. >> did you ask corey out for thanksgiving dinner prior to calling on -- >> i may have mentioned it, but i don't i didn't ask her a direct question. >> reporter: but to the detectives, what the dishwasher did next was a move straight out of a norman bates' playbook. >> he made this really nice thanksgiving dinner in hopes

that he could call her and say, i've made thanksgiving dinner. i'd like for you to come over and enjoy thanksgiving dinner with me. >> reporter: so he made the dinner first? >> yes. >> reporter: and then called? >> right. >> reporter: that's a tiny bit on the creepy side. >> yeah. it was a little strange. >> reporter: it was clear he was infatuated. >> do you think that you were obsessed with her? >> i was slightly obsess. >> you were greatly obsessed, eric. jesus. admit it. my god. >> i was. i was obsessed. >> reporter: from there, the interview took an even darker turn. the young man admitted to violent fantasies. >> tell me the thinks that you think about doing with women that you wouldn't do because you know it's not the right thing to do. >> you like take them into a bedroom and just rape them? >> yeah. >> reporter: he's talking about rape. that's scary stuff right there. >> exactly. >> reporter: that paled in comparison to what he said next. he described how he thought

>> how would you contain her? >> taking her down until she was tired. and just poked her, you know, whatever, stabbed her. >> reporter: in fact, that's how corey was kill ed. did you think about the scenario that he might have felt really rejected by corey and he snapped? >> anything is possible, yes. that comes into your mind that he asked her multiple times to go out with him. although she was cordial to him, she never went there. >> you sound like you know a little bit more of what happened to corey. how would you -- >> how would i know? because maybe -- maybe i would share the same thoughts as this person that did it. >> reporter: he sounded like an obvious suspect. >> i would like to have fantasized myself doing it instead of him doing it. but i didn't do it. >> reporter: despite all his incriminating descriptions, the dishwasher was adamant he hadn't killed corey. and police didn't have any hard evidence that put him inside her bedroom.

and you got nothing to put him there. >> reporter: for the time being, police had to let the man go. just when it seemed their case couldn't get more complicated, it did. corey's friend had been talking around town about the murder, and she was saying all the things that catch a detective's attention. coming up -- are you ready for another potential suspect? this close girlfriend of corey's. was she a little too close? >> tiffany was infatuated with corey? >> yes. her statements about how much she loved corey piqued our interest. ♪ walgreens has all the beauty products you need for whatever makes you feel beautiful.

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>> to that end, everybody who presented as a potential suspect, they were running that to ground. could it be this person? is it this person? >> reporter: amy lavin found herself looking around at corey's other friends and wondering could it be one of them. >> everybody was an actual suspect. so that became a little bit scary to me. >> reporter: her killer could have been right under your nose? >> yeah. >> reporter: tiffany zienta remembers just wanting to be helpful like most of corey's friends, she met with the detectives. they want to talk to you, detectives? >> we all made a statement. >> reporter: well, they wanted to talk to you? >> absolutely. >> reporter: tiffany told the detectives she'd been with corey at the ritz bar wednesday night into the early morning hours of thanksgiving. she said they left the bar at the same time, around 1:30 a.m. tiffany hitched a ride with another friend to go bar hopping. corey, she noted, got into her own car and headed home. later, tiffany said, she called

>> it was like 2:15. it was right after we left the original bar. >> reporter: detectives followed up on what tiffany had told them. carlyle says they quickly noticed a wrinkle in her story. >> her phone call was not on the phone records of corey parker's home residence phone. >> reporter: so she's starting to make some inconsistent statements. >> exactly. inconsistent statements. >> reporter: more troubling to police was what they were hearing from corey's friends. they were saying tiffany had been describing the murder, the stab wounds to the body, details that hadn't been made public. they also believed she harbored deep feelings for corey that weren't mutual. tiffany was infatuated with corey? >> yes. >> reporter: what were you told? >> we were basically told that it was bordering on a little strange, you know, with what we heard about her stramts about how much she carry cared about corey and how much she loved corey, it piqued our curiosity and interest. >> reporter: now detectives

wanted to sit down again with tiffany, but by then more than five months had passed since corey's murder, and tiffany had left town. for new orleans. the move only made her look worse to police. so they tracked her down hoping to confront her, but tiffany wasn't having it. >> she at some point decided she wasn't going to cooperate further and referred us to her lawyer. >> reporter: so detectives decided to get a warrant for tiffany's dna. >> we had to get a court order to get her standards, her hair, and her blood. >> reporter: are you starting to think she could be corey's killer? >> well, you just have to follow that lead. we felt like, based on what we knew to that point, that she was a person of interest definitely. maybe a viable suspect. >> i'm not the person that's going to kill somebody. >> reporter: looking back, tiffany is convinced detectives set their sights on her from t

the fact that she was the last friend to see corey alive, she says, shaped everything that followed. >> i never knew that saying i was the last one with her was going to come back to haunt me. you know? police were like, well, the killer was the last one. until you think about it that way, you don't think about it that way. >> reporter: first of all, she says, she never lied about that call to corey. no matter what the phone records said. how do you explain that? >> according to my attorney, he had had other clients that had called people that didn't show up on phone records either. i don't know. i don't know why it didn't show up. i have no idea. >> reporter: as for being in love with corey, is there any truth to that? >> no. because i'm not gay. i thought she was beautiful. i thought she was a great person. have i been infatuated with corey? no. >> reporter: everything else she did in this case, she says, was

she learned about the bloody crime scene from a friend, a paramedic who had been there. she went to new orleans to rest, not escape. she found a lawyer out of fear, not guilt. how are you feeling as this is getting more intense? i mean, this is a murder investigation. >> helpless. bullied. helpless. like there were going to be no answers. and this was going to hang over me for the rest of my life. >> reporter: but before they could make an arrest, detectives needed to link her dna to the crime scene. that's when things got really interesting. coming up -- yet another person of interest. this one lurking in the shadows. >> it wouldn't take much if she had her lights on for him to sit up there in the dark and be able to watch her. >> and then detectives get their

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♪ we are farmers. bum-pa-dum, bum-bum-bum-bum ♪ jacksonville beach had been home to tiffany zienta. now it seemed home had turned on her. did you think there's a chance i could get arrested? >> yes.

>> reporter: but she wasn't arrested and neither was anyone else in the months following corey parker's murder. a year went by. state attorney angela corey. so this wasn't solved after the commercial break? >> oh, no. no, no. we went into this knowing we were in for the long haul. with that phrase we knew it was going to be a marathon, not a sprint. >> reporter: they had their list of possible suspects, but they didn't have the evidence or the science yet to definitively link anyone to the crime. >> dna testing was actually in the middle of evolving at that time. >> reporter: eventually the science and the evidence came together. investigators recovered a strand of foreign hair from corey's underwear. they believed that single strand was rich in dna. >> it had been clearly ripped out of a head. >> reporter: likely, they believed, the killer's head. now they had to test it against their possible suspects.

>> locked in a tube. >> reporter: didn't know his name? >> hairs on slides, that's right. >> reporter: that's when the case took its most dramatic turn yet. thanks to this man. would you call yourself a bounty hunter? >> i've been called bounty hunter before, but i'd prefer fugitive specialist. >> reporter: fugitive specialist. okay. william rensler knew about corey's murder and he knew there was a reward posted for information leading to her killer. so kind of like, hey, why not take a look? >> yeah. >> reporter: so on his own he started talking to corey's old neighbors to see if officers had missed anything. >> when i came across the one individual, something struck me as odd. >> reporter: the individual was a young man named robert denney. he was 17 years old living in a nearby building when corey was killed. he'd been questioned and dismissed by detectives early on in part because he was so young. what seemed odd to william was

long after the murder. as memorial day weekend rolled around, william found himself on a dock with two friends. >> we were fishing and then having a couple of beers. and i was going over my notes. >> reporter: suddenly, he remembered that robert denney had worked at the same restaurant as his friends. they recognized the name instantly. >> they felt that he was an offbeat individual. >> reporter: about two months after the murder, they said denney seemed distraught saying he had to go home to texas, that his child had just been killed. they quickly found out that he'd made it all up. so he's a liar? >> correct. >> reporter: he lived near the victim. >> correct. >> reporter: he moved out of town shortly after the murder. >> correct. >> reporter: what does your gut telling you as you're sitting on that dock? >> it's highly unusual and we're probably on to something. >> reporter: william shared his suspicions with detective katie kingston. she then went over to check out denney's old apartment for herself.

>> you can see how close it is. >> reporter: it was apartment number 4 and its back balcony was less than three feet from corey's old kitchen. when police met with denney's co-workers, they said he had talked about watching a young woman from his balcony. do you think he'd been watching her for a while. >> yeah. >> absolutely. no question about it. >> reporter: something straight out of hitchcock. rear window, a vulnerable young woman, a man watching, seeing but unseen. denney didn't match the description they'd gotten earlier of the case of the peeping tom, but that didn't mean he hadn't been spying on corey, said detectives. >> it wouldn't take much if she had her lights on to sit up there in the dark and be able to watch her as much as he wanted to. >> reporter: kingston didn't know where the man lived now, but she found out he had a sister in the area. what the woman told the detective about her brother was unsettling, to say the least. >> she called him the night creeper. she said that he would creep around the house at night.

was staring at her. >> reporter: the sister said kingsston could find her brother in eeston, maryland. he'd moved there to be with a woman he met online. kingston and carlyle immediately headed north. they needed to compare their suspect to that hair sample from the crime scene. you need his dna? >> absolutely. >> reporter: with the help of easton police, they called up their suspect and flat-out lied. they made up a story about a recent assault. could he come in for questioning. >> so he agreed to come in and he sat down with us. >> reporter: what followed was vintage cat and mouse. police tried to get denney's dna off a cigarette. denney went for the smoke but when he was finished -- >> haddy took the cigarette butt and put it behind his ear. wouldn't put it in the cigarette ashtray. >> reporter: so they moved on to plan b. they offered him a bottle of water. >> he takes the water, but he doesn't take the top off of it. he sat there the whole time never drank from the water bottle.

>> reporter: which was this. they asked denney to fill out some forms. police procedural stuff, they said. >> and what we were going to do is have him sign those forms and then put them in an envelope and then seal the envelope. there was three different envelopes. >> reporter: denney filled out the forms but didn't lick the envelopes. >> and he looks at us and says, you guys have tried three separate times to get my dna sample. he says, you can seal them yourself. is there anything else? >> reporter: the best laid plans. >> the best laid plans of mice and men. he didn't fall for it. >> reporter: denney was done, but carlyle wasn't. >> i wasn't going anywhere without a dna sample. >> reporter: so they staked him out at the computer store where he worked. and snapped these photos as their prey came outside for his cigarette breaks. once again, their mouse was a step ahead. >> he was smoking a cigarette and when he was finished with it, he would take it and put it behiis

knew that maybe you were watching him? >> i'm sure. >> reporter: but on the second day, denney did something he had probably done a thousand times before. >> he starts spitting on the ground out of the clear blue. >> reporter: spit has dna in it. >> and we were like -- we were jumping for joy at that point. >> reporter: so you've never been so happy in your life to see someone -- >> never so happy to see that. >> reporter: -- spit. when denney was finished carlyle raced over, took a sample and went straight to the fbi's dna lab. all there was left to do now was wait just a little bit longer. coming up -- no matter how the tests come back, detectives will have to explain a lot of other evidence at the scene. >> there's unidentified fingerprints and there's unidentified hairs in the victim's hands. >> had someone else been at corey's? then we sit down with robert denney. >> did you murder corey parker? >> the reason denney says police

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it had been a year and a half since corey parker's murder when police discovered or rediscovered robert denney, her old neighbor. >> we went full bore on robert denney at that point. >> reporter: here's why. denney lived right behind the victim. he disappeared soon after her murder. and detectives learned this. denney had an older brother in prison for murder. you're starting to think this might run in the family? >> you can't help but think that. >> reporter: denney's brother

in texas. and his crime was eerily similar to this case. >> the interesting thing about the brother was that, in his case in el paso, he stabbed that woman 96 times. and we're dealing with a homicide where our victim's been stabbed 101 times. so the similarity was just too much to overlook. >> reporter: the detectives had to wonder if denney had killed corey in a twisted attempt to outdo his sibling. one thing detectives were sure of, he had become fixated on her. a co-worker recalled being in robert denney's apartment. >> robert pointed down to corey's window and said, i watch that girl down there. >> reporter: they were convinced denney was her killer, but they needed proof. so they waited for tests to compare denney's saliva sample to that strand of hair found at the scene. and wouldn't you know, denney's dna was a match. not just to that hair but also to a tiny speck of blood

all the other possible suspects, the next-door neighbor, dishwasher and tiffany, were cleared in the case. >> we were jumping up and the down. >> we wanted to go get him then. >> reporter: and prosecutor angela corey said no. >> he can come up with a story to explain that dna away. i carried her groceries in for her and i cut my finger. kaunt give anybody a chance to explain it away. >> reporter: the prosecutor wanted him on the record denying he'd ever set foot in the victim's apartment. then they'd hit him with the dna proof trapping him. so they sent katie kingston back to maryland to robert denney's house. >> well, i was going to play like i didn't know anything. >> reporter: you were acting. >> just acting kind of dumb. >> reporter: she told denney they had found the man who killed his old neighbor corey parker. the detective was just here to tie up loose ends. he seemed willing to help.

detective was wearing a wire. >> dna of corey parker? or ever talk to her? >> no. >> okay. no. >> reporter: then the detective asked the crucial question. had he ever been in corey's apartment? you all didn't go back and forth to each other's apartments? >> i knew the guy next to that. >> reporter: so you all didn't go back and forth. >> reporter: that was all the detective needed. the cat it seemed had finally gotten its mouse. >> when i heard the recording, i had the arrest warrant ready to go and i finished plugging in what they told me over the phone, and we were ecstatic. we knew we had him. >> reporter: corey parker had been dead almost two years to the day when police slipped the handcuffs on robert denney. at the police station right after his arrest, he protested his innocence.

it's impossible. because i didn't do it. >> reporter: and when carlyle mentioned denney's brother he again told detectives he had it all wrong. >> that's my brother. >> i understand that. >> that's my brother. >> i understand that. >> that's not me. >> reporter: they had enough to put robert denney weigh away for life. it took fine years to come to trial. it was a complicated investigation. denney's dna was found at the crime scene but there was also evidence they couldn't link to him. >> we had alternative suspects. we had a lot to explain in the form of the science. >> reporter: the defense seized the opportunity noting there were any number of people who might have killed corey. >> there's still unidentified pieces of evidence at this crime scene. >> reporter: robert denney's attorney, rick sitka. >> there's unidentified seme

stains and fingerprints and hairs in the victim's hands. so it's a question of who done it. >> reporter: not a case of denney did it, he said. to underscore that, denney even took the stand to show jurors he was just a boy next door, not a monster at the door. only it didn't work. after a three-week trial, the jury needed less than an hour to render a verdict, guilty of first degree murder. denney was sentenced to life in prison. which is where we met for this interview. did you murder corey parker? >> no, i did not. >> reporter: he believes the sins of his brother made police quick to zero in on him. there has been a connection made as far as the theories of the police, the prosecutors that this was some twisted brotherly bond or rivalry. is there any truth to that? >> none at all. simply because my brother is convicted of murder doot

>> reporter: he says the way police later got his dna shows they were determined to link him to corey's murder. >> when i first heard that my spit was what they collected to match to any dna at the crime scene, it was just unreal. i'm thinking to myself, how could this be? >> reporter: he's also convinced that the labs, including the one at the fbi, didn't follow protocol when they tested his dna from the crime scene. >> there was evidence to suggest that they may have mixed up samples. >> reporter: the hardest part to mix your head around is there can be contamination on both the blood and the hair. >> right. i can understand why you would feel that way and maybe that goes to explaining what the police might have done with the evidence. we don't know. if i knew, i wouldn't be here. >> reporter: it just seems a little far-fetched that the police would randomly pluck you out of obscurity y

>> i understand. and i thought about this for years, and it happened. police do frame people. we see it all the time now in america. >> reporter: the police have framed you and two separate crime labs have contaminated the evidence? >> yes. >> reporter: you can see how that -- >> i can see how that is -- >> reporter: very far-fetched. >> far-fetched. yeah, i can understand that. >> reporter: the detective in this case says he is 1,000% certain he has the right person. >> he's wrong. he does not have the right person. >> reporter: so who did it then? >> if i knew, i wouldn't be here now. i wish i knew. >> reporter: yet the people who arrested and prosecuted denney insist two independent labs did follow protocol linking his dna to evidence from the crime scene. still, denney is hoping a recent post-conviction motion arguing in part th t

flawed will result in a new trial. his family and supporters are even blogging about his case. that infuriates corey's friends. >> i hope he rots in hell. i hate robert denney. >> reporter: as for tiffany zienta, she says it took a long time to get over what he and the police did to her. how did you deal with it? >> drink. more. tried to lose who i was. tried to change who i was. didn't like myself very much. it's taken me a while to get back to who i need to be. >> reporter: amy lavin has also struggled with the past. >> i go to that day. why didn't i invite her to thanksgiving with me. maybe she would have gone. even to this day, there's a lot of guilt with that. >> reporter: but there's also gratitude to investigators who never gave up, to three strangers on a dock playing arm chair detective and, most of

>> i definitely feel blessed to have known her for the amount of time i did. i can't imagine what she would have accomplished by now. >> reporter: whatever it was, amy feels certain it would have been like the woman herself, as vibrant as a northern sky, as unforgettable as a southern night. that's all for this edition of "dateline." we'll see you tomorrow at 8:00, 7:00 central for the dateline saturday night mystery, then again sunday at 7:00, 6:00 central for on assignment. i'm lester holt. s r all of u

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