In this special 100th edition of Cold Case Files, we look at the biggest serial murder case in U.S. history - the 20-year hunt for the Green River Killer. Dave Reichert, the detective who made finding the killer his obsession, walks us through the case. He tells vivid, sometimes harrowing stories about the murders, saying, "You never forget the sight of a 16-year-old body lying on her back on the riverbank with ligature around her neck." Reichert headed up two Green River task forces until forensic DNA technology helped crack the case and brought him face to face with the killer thought to be responsible for 48 deaths.

A 14-year-old boy is charged with the murder of his sister, but his public defender believes the police coerced the boy's confession and that the real killer is still on the loose. And two deteriorated medical examiner's slides, made in a murder investigation 16 years earlier, give police the evidence they need to reopen the cold case and bring the lead suspect to trial.

After U.S. Navy sailor Andrew Muns disappears in 1968, the Navy claims that Muns went AWOL from his ship. But his sister works tirelessly for over 30 years to prove that Muns was really killed. And DNA surreptitiously gathered from a cigarette butt helps detectives to unravel a 20-year-old case of rape and murder.

Our cameras follow Detective Manny Reyes as he investigates the 1990 murder of a Fort Worth, Texas woman. Reyes talks to the woman's two sons, who believe that her husband, Bobby, was the murderer. We then watch as one of the husband's relatives tells Reyes that Bobby has confessed the crime to him. To make the case even stronger, Reyes collects physical evidence that connects him to the crime. Finally, Reyes meets Bobby for a dramatic interrogation. Will he crack and admit the crime--or will he hang tough and deny it all?

The killing of a woman in a Virginia hotel room goes unsolved for a quarter of a century before investigators are finally able to zero in on the likely killer. And, when a 25-year -old women is shot to death during a jewelry store robbery in 1980, investigators collect fingerprints and blood from the crime scene. There are few leads and the case goes cold until 1999, when detectives test the blood evidence and develop a DNA profile. For two years more, that profile sits without a match, until 2001 when a convicted burglar is entered into the DNA databank.

When an adulterous church deacon is found shot to death in the back seat of his car, it looks like police may have stumbled upon a multi-party murder plot. And, a wife remains a key suspect in her husband's murder case for six years, until she takes the matter into her own hands to prove her innocence.

The dogged work of an Alberta, Canada, detective finally pays off when he tracks down the man who raped and murdered a 6-year-old girl 10 years earlier. And when police search for the killer of an 18-year-old hitchhiker, they find that the victim's diary is one of their best clues.

The story of the hunt for one of the most notorious serial killers in recent American history--the BTK killer, who terrorized the Wichita, Kansas, area for years. After committing at least seven brutal murders, BTK (for Bind, Torture, Kill) vanished for over 25 years before sending clues of his crimes to the media in 2004. He continued to avoid capture until a forensic computer expert traced a computer disc that led investigators to a surprising suspect--a church president.

A district attorney uses a clever technique--a "John Doe indictment"--to give law enforcement officials the time they need to track down the Schoolgirl Rapist from Rochester, N. Y. And prosecutors reluctantly decide not to prosecute their lead suspect in the rape and murder of a 9-year-old girl because they have only circumstantial evidence. But 12 years later, the cold case squad reopens the case, hoping DNA evidence will prove the supect's guilt.

Bill Kurtis examines one of the most infamous cold cases in Los Angeles history -- the 1947 murder of actress Elizabeth Short, who was found nude and cut in half in an empty lot. Though charges have never been filed in the case, theories abound, and Kurtis investigates some of the most prominent ones. He talks to a retired LAPD detective whose 3 year investigation led to the stunning conclusion that his own father committed the murder. Kurtis also probes the theory that the killer was a surgeon named Walter Bayley. Kurtis finally explores the possibility that there may have been a police cover-up in the case to protect the real killer.

DNA found on a marijuana joint in Florida in 2005 helps to solve the 1988 rape and murder of a California woman. And a cold case of murder in Illinois heats up when a jailhouse lawyer turns jailhouse snitch.

Detectives are baffled when two young girls are raped, murdered, and dumped in an abandoned house in Akron, Ohio. And a 26-year-old mother of three disappears on Christmas Eve in 1995, but the missing persons case goes cold when police can find few clues to her whereabouts.

Thirty-two years after the killing of University of Michigan law student Jane Mixer, police use DNA found on her pantyhose to finally track down the killer. And psychologists help solve a cold case by suggesting the lead detective take a page from the game of romance, and play hard to get with the killer.

A video tape made at an ATM machine helps police in Louisville, KY, to nab a man suspected of raping 13 women. And a DA investigator in Georgia helps crack a murder case that his father, a police chief, first worked on 30 years before.

Law enforcement officials fear they may have to release a serial killer from prison until a 24-year-old murder case gives them a chance to lock him up for good.

This special edition of Cold Case Files offers an inside look, rarely seen, at an active cold case investigation. We follow Det. Vince Velazquez of Atlanta and Capt. Russell Popham of East Point, Ga., as they work to solve the 1995 rape and murder of 14-year-old Nacole Smith, one of Atlanta's most notorious unsolved crimes. We see Velazquez and Popham hit the streets to question people who might recognize the man in their composite sketch, and obtain DNA samples from potential suspects. "It's almost like the carrot's dangling in front of us, but we just can't catch it," Velazquez says of his painstaking, frustrating search for the killer.

Included: a man is suspected of killing his wife. Also: the case of a mother who vanished on Christmas Eve in 1995.

On a summer night in 1987 a mother worries and waits for her 19-year-old daughter to come home. But Diana never comes home and she's found raped and strangled near the Hudson River. Investigators suspect her friend, Michael because his alibi is shaky and witnesses place his truck near the crime scene. Trouble is, he passes a polygraph and his DNA is no match. Nevertheless, Michael remains the chief suspect for 17 years, until DNA fingers another man who offers a chilling story of Diana's last breath. Then, a young family's life is shattered when a San Antonio interior design shop becomes a crime scene. In 1983, a young mother is raped and murdered at work. The crime remains unsolved for two decades. Then in 2003 detectives reopen the case pegging their hopes on DNA. But when the evidence turns up missing, detectives worry this case could be over before it starts.

A serial rapist seals his own fate when he sends a taunting letter to police, who use the DNA extracted from the saliva in the envelope's seal to track him down. And when a man is found dead in South Dakota, his head bashed in by a 50-pound rock, investigators go on a 20-year search for the killers--a man and woman who were part of a free-loving hippie group and are known only by the names "Outlaw" and "Inlaw."

Nine years after the murders of a mother and her teenage daughters, a wiretapped conversation between the suspected killer and his sister helps police to crack the case. And the baffling murder of a Virginia woman is solved when human bones are discovered by a geologist working in North Carolina.

In Rhode Island, policewomen go undercover in as street walkers to nab the man suspected of murdering three prostitutes. And a dagger-shaped letter opener is the key piece of evidence that links a priest to the grisly 1980 murder of a nun in Toledo, Ohio.

Police in Albany, N.Y., get a surprise when a killer they think targets only older women is suspected in the murder of an elderly man. And the contents of a secret storage shed holds the grisly clues to a murder that has gone cold for more than 14 years.

After 19 years, Kansas detectives reopen the case of a banker found beaten to death in his bed--and the chief suspect is his cheating wife. And a man with a guilty conscience helps Arkansas police to crack a cold case of murder when he tells them that his ex-wife knows who the killer is.

In the first case in this episode Felicia Prechtl is found raped and murdered in Dallas, Texas/ The only thing the killer left behind was a fingerprint which was smudged. The fingerprint was left on a piece of duct tape that the killer used to tie up Felicia. It would take many years before Felicia would get justice. It would take the work of a dedicated detective to runs the prints through the system and find not only a match to the print but also finds the killer. And he wants to confess. The second story in this episode is about a little girl, Surrette Clark, who lived in the Arizona desert. She disappeared with nobody to even recognize that she was gone. After Surrette went missing at the age of 3 it would take more then 20 years to solve this mystery. Her parents took off across the Canadian border right after her disappearance. Finally a woman comes forward to tell of the families secret. With this information cold case detectives find out about a story of child abuse and how deadly some people will go to hide them. The third story in this episode is about a known man. One who has passed through our live via television either from watching the show or somebody talking about it. Its Bob Crane. Best known for his role on Hogan's Heroes as Colonel Hogan. Crane was strangled and beaten to death in his own bed in 1978. The story goes that Bob and a friend of his had a fight one night. With the small evidence that the police did have the police suspected his friend of his murder but could not prove it. It would be 12 years before anybody takes a second look at this case. On the second try police do find the evidence they need but will it be enough? In the fourth installment to this episode is about Ronnie Bullock. He was a man who had served 10 years of his sentence for raping an 11 year old girl. Through the entire time of his imprisionment he stayed stedfast to his claim of innocence. It would not be until DNA was founded that someone would listen to him and prove him innocent.

The Boy and the Monster In Wisconsin in the winter of 1991 a young woman's body was found naked, badly beaten and to make it harder to identify her, her fingertips were cut off. After months of trying to figure out who she was they finally came up with a name. Doris McLeod. After finding out who she was the police find out a lot more about her. She had a troubled past. After being on the streets she ended up connected to a pimp. Only one month of being on the streets she is never seen again. It takes a 3 year old boy to finally tell the police about Doris and the Boy and the Monster. Secret in the Cellar The second part of this episode is about a young woman from South Portland, Maine who was in search of her mother. She contacts the police but they get nowhere. They question Bill Bruns, the missing woman's husband who told the police a story about how Pearl drank and ran off with another man. Elaine Woodward, the missing womans daughter, went to the media for help. An investigator takes the case and with the help of science and man power he finds out what happened to Pearl with the Secret in the Cellar.