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Colorado detectives investigate the decades-old disappearance of 12-year-old Jonelle Matthews.

Police are perplexed when they find the body of a young woman but are unable identify her. With the help of amateur internet investigators and new DNA technology, a dogged investigator finds her killer ? and her identity.

Judy Carlson lives in a painful limbo. Her son disappeared without a trace. Years went by and she may never have known his fate if not for a rookie detective's dogged work, but to solve this cold case, the investigator also needs the help of a killer.

Two arsonists are arrested; armed robbers strike a hotel; a father seeks his daughter. Also: ghost sightings aboard the Queen Mary.

Hollywood stuntman Garret Warren's shooting attack is investigated.

Michelle Young, married to her sweetheart and pregnant with their second child, is murdered. In the search for her killer, detectives uncovered a marriage riddled with secrets but solving this complicated case took years.

Detectives and forensic experts recount cold cases solved using familial DNA testing.

In 1973, two young girls are found murdered in the Welsh village of Llandarcy. The killer's identity remains a mystery until 2002.

The episode follows the 17-year police investigation and how detectives tracked down a serial rapist.

In Colorado in 1996 a young woman's body was found in an alley. After the case goes cold advancements in genetic technology lead police to the killer.

The episode follows the 17-year police investigation and how detectives tracked down a serial rapist.

In Colorado in 1996 a young woman's body was found in an alley. After the case goes cold advancements in genetic technology lead police to the killer.

Publicly they were a prominent family highly respected for their success. But privately a jury heard something else. It was case that pitted father against son, husband against wife and brother against brother.

Dateline NBC, or simply Dateline, is a weekly American television newsmagazine series. It was previously the network's flagship newsmagazine, but now focuses mainly on true crime stories with only occasional editions that focus on other topics.

It was a mystery from day one: a young father's life cut short. How Matt Podolak died was curious. The word poison kept coming up. Matt's brother would embark on a long quest for the truth.

Authorities are alerted after a pastor loses his second wife in a freak accident.

A look at the people who might have been responsible for the disappearance of a free-spirited woman.

A young model vanishes near Los Angeles; a woman probes her grandmother's disappearance. Also: claims concerning the role of a faith healer in a little girl's recovery.

Ghostly phenomena linked to a Civil War museum. Also: a rape suspect flees; a witness in a case against a car-theft ring vanishes before he can testify.

A purported haunting in a comedy club; claims of frauds perpetrated by a mother and daughter. Also: an attempted robbery at a furniture store is linked to the shootings of a man's wife and in-laws.

An alleged UFO sighting in the UK; claims of sexual and physical abuse by a cult leader; a religious student's murder. Also: a woman vanishes after arranging to meet with her ex-husband.

A man goes missing after getting drunk and taking a swim in a river; a missing daughter calls her mother seven years after disappearing; a love story unfolds.

The episode follows the 17-year police investigation and how detectives tracked down a serial rapist.

In Colorado in 1996 a young woman's body was found in an alley. After the case goes cold advancements in genetic technology lead police to the killer.

New DNA technology help uncover the truth behind a cold case of a 69-year-old woman who was killed in 2011.

Following the decadeslong investigation into the murder of Helene Pruszynski.

New DNA technology help uncover the truth behind a cold case of a 69-year-old woman who was killed in 2011.

Following the decadeslong investigation into the murder of Helene Pruszynski.

An in-depth look at the journalists who exposed the dangers of cult leader Reverend Jim Jones; interviews with witnesses to murders carried out by Jones' followers.

Profiling the case regarding a single dad and former firefighter who was found dead in his garage.

Investigators unlock a tool that may help unveil the identity of a schoolteacher's killer.

Ghostly phenomena at Moss Beach Distillery in California. Also: a university student vanishes after embarking on a cross-country trip; a newborn's miraculous recovery baffles doctors.

A baby's miraculous recovery; a liquor store owner's murder. Also: a man dies from carbon dioxide-poisoning in his garage; a bogus company is set up to bilk investors out of millions of dollars.

A con artist's scam; the death of a Los Angeles DJ. Also: children begin to contract leukemia in a small Nevada town.

A mysterious humming sound torments thousands across the globe; a husband and wife are wanted for the murders of the wife's aunt and uncle; a Phoenix man vanishes.

Psychic Edgar Cayce. Also: a woman goes missing after being seen at work; a man disappears after attending an off-campus party.

Newsmagazine that delivers viewers stories ranging from mysteries to documentaries.

When Michele is found dead, police officers uncover a fatal betrayal.

Police suspect natural causes as they investigate a man's death, until they they uncover a love triangle that turns the tragedy into a tangled mystery. Andrea Canning reports.