came together. >> i've never had a case where the small things mattered so much, where something as small as a needle mark or the amount of dna left on a needle cap played such a pivotal role in the resolution of a case. up next, a murder that stumps even veteran detectives. >> it was a nasty, nasty crime scene. >> and the crime that offers few clues. >> there were no signs of any struggle or fight. >> was this a sex crime by a jilted lover? >> her body was positioned in a way that was very sexually suggestive. >> it's hard to imagine anybody is capable of something like this. >> until one man's words reveal a twisted motive and a killer with a bizarre past. ♪ jacksonville, florida, with its warm, sandy beaches and

subtropical climate, was the perfect place for 25-year-old corey parker to attend college. she liked it a lot better than the cold winters of her hometown of rochester, new york. >> corey was beautiful. she was very tall. she had a presence about her. some of our best times together was a girl's night in, you know, rent movies and go hang out at the house. >> corey worked her way through college as a waitress. during the thanksgiving holiday of her junior year, she didn't show up for work, so her fellow employees were concerned. >> they thought immediately that something was wrong. so the manager directed one of the cooks to go by her apartment to check on her. >> her apartment door was locked, but her co-worker looked inside and saw her body on the bed, covered in blood. >> this crime scene was one of the worst that this county has ever seen in terms of its just

gruesomeness. there was blood all over her bedroom, all over her body, almost as if it had been painted on her. >> the scene appeared to be staged. >> corey's body was positioned in a way that was very sexually suggestive. she was nude. her legs were spread apart. there's every indication that there was a sexual motive to this crime. >> interestingly, the autopsy found no evidence of sexual assault. >> corey parker was stabbed 101 times. of those 101 stab wounds, i believe 54 were postmortem. overkill does indicate to investigators a relationship between victim and perpetrator. >> police learned that the night before her murder, corey spent the night at a local bar with friends. witnesses said she left around 1:00 a.m. the clothes corey wore to the bar were folded neatly at the bottom of her bed.

>> we also know that she had prepared herself for bed and crawled in her bed, so we know she wasn't attacked until after she was in bed. so either he was waiting in her bedroom closet, or he let himself into the apartment. >> investigators found a gold-plated zippo lighter in corey's bedroom. although corey smoked, none of her friends recognized it. investigators dusted the lighter for fingerprints, but none were found. >> it became apparent to us that there was no way that that was corey parker's lighter. >> inside the kitchen of corey's apartment, police found a bloodstain on the kitchen counter next to the sink and on the windowsill above the sink, both inside and outside. this led police to believe the

killer entered and exited the apartment through the kitchen window. >> the reason we believe the killer didn't go out the door was because of the light that was outside. the kitchen window offered the suspect a way to both get in and out of the apartment without being illuminated. >> corey's phone records revealed that a former co-worker, 27-year-old eric jones, had been calling her repeatedly before her death. >> he had been asking corey out for some time. she had been telling him no. >> employees at the restaurant told us that he had an obsession or an infatuation with her and was continuously talking to her when she'd come to work or trying to ask her out. >> jones had no criminal record, but acted bizarrely when interviewed by police. >> not only did he have a

history of mental illness, by his own admission, but he told police officers that he had fantasies about raping and killing women, which clearly jumped out at law enforcement. >> he described sexual fantasies he had about corey. some were fairly violent. >> he even told investigators how he would have murdered corey had he been given the chance. >> he described how he would have slit her throat early in the murder so that she couldn't scream for help, and that description was similar enough to how she was really killed that it, again, raised police suspicion. are you so congested... it feels like that brick's on your face? try zyrtec®-d to powerfully clear your blocked nose and relieve your other allergy symptoms. so you can breathe easier all day. zyrtec®-d. find it at the pharmacy counter. 8 layers of wheat... mini-wheats®... and one that's sweet. for the adult.... and kid - in all of us. (supergrass' "alright") (plays throughout)

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the medical examiner who performed corey parker's autopsy found no signs of sexual assault, but corey had been stabbed over 100 times. there were numerous defensive wounds on her hands and arms, proving there had been an intense struggle. >> our theory was that corey parker fought for her life in order to prevent a sexual assault. >> investigators found several

foreign hairs in corey's hands. one had an intact root. >> the fact that the hair had root material on it and was not from her would allow you to at least presume that that hair had to be obtained forcefully. >> dna testing revealed the blood in the kitchen came from the same person as the hair in corey's hand. surprisingly this dna did not match the prime suspect, eric jones, corey's co-worker, despite his bizarre behavior. the dna from corey's apartment did not match any of the dna profiles in either the state or national criminal databases. in the search for corey parker's killer, investigators discovered that she had just started dating someone new. his name was david wilt. but it didn't take long for investigators to eliminate him as a suspect.

>> he was out of state at his parents' house for thanksgiving, and so, you know, he had a very solid alibi. >> investigators interviewed everyone corey spoke with at the ritz bar on the night of her murder. most of the people corey saw that night left the bar before she did, but one friend, tiffany smith, stayed with corey until 1:00 in the morning. tiffany told police they both left the bar at the same time in their own cars and went their separate ways. but tiffany told friends that wasn't the only contact she had with corey that night. >> she said she called corey from her cell phone around 2:00 a.m. and corey answered the phone. she said when corey answered the phone that corey was asleep and she asked her what she was doing. corey said, i'm sleeping. >> tiffany also told friends she drove to corey's apartment around 4:00 a.m. and knocked on

her door, but no one answered so she left. >> her statement that she went by corey's house puts her at the crime scene during the time that corey could have possibly been killed. and that added to that suspicion that she could possibly be involved. >> but when investigators checked tiffany's cell phone records, they made a startling discovery. tiffany didn't call corey after they left the ritz bar. but why would tiffany make up a story like that? >> everybody was talking about the possibility that maybe she was sexually interested in corey. tiffany mentioned to me in just a very casual conversation that she had been vicarious. >> tiffany had a real, true affection for corey. >> in addition, tiffany told friends things about the crime scene that had not been released

to the general public. >> she was describing the state of the victim's body and the scene without having been privy to either photographs or a walk-through of the scene. they thought it was certainly suspicious. >> tiffany denied any involvement in the murder, but when asked to provide a dna sample, she refused. >> the fact that she did not willingly give up dna or hair samples led the police to believe she had something to hide. with type 2 diabetes, you're certainly not alone. fortunately, many have found a different kind of medicine that lowers blood sugar. imagine what it would be like to love your numbers. discover once-daily invokana®. it's the #1 prescribed in the newest class of medicines that work with the kidneys to lower a1c. invokana® is used along with diet and exercise to significantly lower blood sugar in adults with type 2 diabetes. it's a once-daily pill that works around the clock.

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even though corey parker's friend, tiffany smith, insisted she had nothing to do with corey's murder, she made untruthful statements about her activities on the night of the murder. she also refused to provide a dna sample. >> she actually put herself at the crime scene in one of her statements. >> but scientists found a surprising piece of information in the blood evidence left by the killer. they found the telltale "y" chromosome. a "y" chromosome is present only in men. >> we did develop a male profile from a blood sample from a point of entry or exit into the apartment. we were optimistic that this could be from the suspect.

>> so tiffany was eliminated as a suspect. >> they believed that tiffany was saying things to kind of inject herself into the investigation to make her seem more important than she was. >> investigators believe tiffany learned details of the crime scene from a friend who worked on the emergency crew. police were forced to consider the possibility that corey's murder was a random act, perpetrated by a man with an uncontrollable hatred for women. eventually police performed dna tests on 38 men, co-workers, fellow students, former boyfriends, with no success. >> i was very concerned that they would never solve the case, and what i learned from watching other crimes is that the longer it goes on, the less likely it is to solve a crime. >> 18 months passed, and police continued to work the case, poring through the file, re-reading the police

interviews. to generate new leads, police offered a reward for any new evidence which would lead to a conviction, and it generated a lead. some employees of a local steakhouse a few miles from corey parker's apartment called police to report that a co-worker, robert denny, behaved suspiciously after corey's murder. >> he just seemed to be upset, was crying, had come into this restaurant one day and told them that his child had been killed in an automobile accident in texas and that he needed to get back home. >> denny's co-workers responded generously by raising money so he could return to texas to attend his son's funeral. >> after collecting that money, the owner of the restaurant went over to give the money to his sister when he was told that robert denny did not have a son and that that story was fabricated. >> and there was something else

about robert denny. he lived in the same complex as corey parker, with a direct line of sight into her apartment. >> robert denny told some co-workers about this woman that lived in an apartment below him, and he began to talk about how he would watch her. and even went so far to graphically describe that he would masturbate while watching her. >> when police decided to question denny again, his sister told police that he'd left the area. >> she had actually kicked him out of the home she shared with her husband because of his odd behavior, staying up all hours of the night, his, what she described as an addiction to pornography. she told one law enforcement officer that she had awoken to him looking over her bed and staring at her.

then police learned another disturbing piece of information. robert denny's older brother was serving a life sentence in texas for stabbing a woman 97 times. >> corey parker was stabbed 101 times. what are the chances of two young men coming out of the same family committing such heinous and atrocious murders, and was he trying to emulate his brother? i told myself for so long that i needed to quit smoking. i would quit then i'd go right back to it. chantix absolutely helped me quit smoking. along with support, chantix (varenicline) is proven to help people quit smoking. chantix helped reduce my urge to smoke. some people had changes in behavior, thinking or mood, hostility, agitation, depressed mood and suicidal thoughts or actions while taking or after stopping chantix. some people had seizures while taking chantix. if you have any of these, stop chantix and call your doctor right away. tell your doctor about any history of mental health problems, which could get worse while taking chantix or history of seizures. don't take chantix if you've had a serious allergic or skin reaction to it. if you develop these,

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18 months after corey parker's murder, investigators found robert denny 800 miles away in maryland, where he was living with a 52-year-old married woman. >> robert denny had struck up an e-mail relationship with a married woman and eventually had convinced her to let him come up there and live with her and her husband. he and this woman had a sexual relationship right under the husband's nose. >> when police questioned denny, they told him they were investigating his possible involvement in a different crime, hoping he'd let down his guard. >> they told him they were investigating a potential allegation that he had been involved in a fight in easton, maryland, which they thought he would voluntarily give his dna to prove he had not been

involved in the fight. >> and we were not leaving easton, maryland, until we got his dna. >> this proved to be harder than investigators anticipated. denny smoked during his interrogation but always made sure to keep the cigarette butts. detectives offered him a bottle of water, but he wouldn't touch it. finally, they asked him to sign a document, saying he refused to provide his dna. >> we asked him to put the letter into envelope and seal the envelopes. he refused to seal the envelopes, and basically told us, look, you tried three times to get my saliva on something. first, the cigarette butt, then the water bottles and now the envelopes. seal it yourselves. is there anything else i can do for you? >> so investigators put denny under surveillance at his home and at the computer store where he worked.

he took a cigarette break every 45 minutes, but was careful to keep the evidence. >> when he smoked his cigarettes, he would put out the butts and put the butts in his pocket so they could not be collected. >> two days passed, and investigators finally got a break. just after a brief rainstorm, denny came outside to smoke, but this time, he did something different. >> he walked around and then all of a sudden, began spitting on the sidewalk. not once, not twice, but six times. >> because of the rain, the saliva was sitting on top of the rain water making it easy to collect. and the barrier helped reduce contamination. >> it was very easy to designate where it was. >> from that point on, it was the same as testing for a hair or bloodstain or semen stain.

>> the results left no doubt. the unknown dna from corey parker's apartment belonged to robert denny. >> the fact that he denied ever having been in her apartment made this evidence all the more incriminating. >> and there was one other piece of evidence that implicated denny, the gold-plated lighter found in corey's bedroom. he said it wasn't his, but a former girlfriend told police it was his lighter. >> she was able to identify the emblem on it. she was positive that was his lighter. >> prosecutors believe robert denny was obsessed with his beautiful neighbor, corey parker, and monitored her comings and goings. he also looked inside her apartment whenever he could.

prosecutors believe denny saw corey get ready to go with her friends on the night before thanksgiving. then, armed with a knife and wearing gloves, he entered corey's apartment through the kitchen window. the evidence suggests he hid somewhere, possibly in her closet, and waited for her to return. corey had no hint that anyone was inside and went to bed. that's when denny attacked. but corey fought back. in the process, she pulled out some of his hair which contained his dna. his lighter slipped from his pocket during the struggle. he stabbed her repeatedly. at some point, he cut himself

and bled inside his glove hand. as he left the apartment through the kitchen window, he left a blood smear on the windowsill, providing his dna. robert denny went on trial for first-degree murder. the jury deliberated for 45 minutes. >> we the jury find the defendant guilty of murder in the first degree as charged. we the jury further find the killing was done with premeditation. >> since he was only 17 years old, a minor, when he committed the crime, denny was sentenced to life in prison without parole. >> methodical in cleaning up, he was careful and he almost got away with murder but for that one drop of blood and hair that he shed that he didn't ever expect to be discovered. >> this girl was a very likable, very intelligent, very beautiful

25-year-old that had a bright future in front of her. she came from a good family and had a good social network. had everything in the world to live for. and in one instance, this cold-blooded killer takes her life. up next, a body is burned beyond recognition. >> there was nothing to identify this person. >> a unique construction material provides a clue. >> this plaster was not like normal plaster. >> i was saying, what is this? it was something i had never seen before. >> but who was the victim? and who wanted him dead? >> i have to somehow artistically interpret what has changed from the fire. ♪ >> just after midnight one christmas eve, motorists along route 83 near baltimore reported