TV Guide Oxygen Sunday

Laura Greenberg's 40-year quest to uncover the motives of killer Doug Gretzler and disturbing new insights into one of America's most shocking killing sprees.

After numerous women are found brutally murdered with their bodies in grotesque positions, police determine they are looking for a specific killer.

When a wealthy man gets a frantic call from his wife that she has been kidnapped, a search for the kidnappers leads investigators to a shocking revelation.

Investigators open a new case after a mother is abducted at gunpoint, but they struggle to discover who kidnapped the victim and why.

A foreign exchange student's dream of studying in America comes true after he enrolls in a Montana high school, but it takes a turn when a walk ends in tragedy.

In Las Vegas, a cocktail waitress is found murdered, but when detectives try to track down her killer, it becomes clear that their investigation has just begun.

When a physical therapist disappears following a boating accident involving her husband, the husband's new love interest leads investigators to the truth.

Emma Coronel Aispuro discusses her dramatic love story with the former leader of Mexico's Sinaloa Cartel, and the impossible choices she was forced to make.

Laura Greenberg's 40-year quest to uncover the motives of killer Doug Gretzler and disturbing new insights into one of America's most shocking killing sprees.

In November 2006, a New York woman stabs her husband to death and claims it was an act of self-defense; allegations of domestic abuse soon surface.

When her husband is discovered dead, investigators suspect his wife, who claims to have suffered years of domestic abuse at his hands.

In April 2012, investigators suspect a San Bernardino, Calif., woman of scheming up the murder of her husband, a local TV repairman.

In the summer of 2010, a North Carolina woman is charged with the murder of her husband after police find his body hidden in their home.

In her first televised interview, Angelina O'Mara attempts to explain the back-to-back 2011 murders of her ex-husband and boyfriend.

Speaking on camera for the first time, Cameo Clines offers a rare look into the events that led to two murders and shares his hopes for redemption.

Rebecca Keller reveals chilling details about the night she stabbed her then-girlfriend's mother more than 70 times; she opens up about her regrets and more.

A bomb rocks Chicago killing Mark Toney, investigators dig beneath the rubble to expose a violent, seductive con game and a shockingly deceitful relationship.

When an Army vet is found dead, it looks like a tragic suicide, but police uncover a sprawling cover-up and two grannies whose dueling stories collide.

Rebecca Keller reveals chilling details about the night she stabbed her then-girlfriend's mother more than 70 times; she opens up about her regrets and more.

A bomb rocks Chicago killing Mark Toney, investigators dig beneath the rubble to expose a violent, seductive con game and a shockingly deceitful relationship.

When an Army vet is found dead, it looks like a tragic suicide, but police uncover a sprawling cover-up and two grannies whose dueling stories collide.

A man makes a chilling confession: he's shot his wife, but what first appears to be a straightforward homicide soon unravels into something far more complex.

Detective work quickly to find the murderer of a young Texas woman whose body is found beaten and bound inside a burned-down apartment building.

Illinois police chase down leads in a case where a mother and son suffer a brutal home invasion, and they unearth a motive with terrifying implications.

Details are shared about a detective who had overcome the odds in her personal life to reveal how she investigated dead-end cases.

Details are shared about a detective who had overcome the odds in her personal life to reveal how she investigated dead-end cases.

When the body of a college student is found in a ditch on the side of the road, investigators discover similar attacks and begin looking for a serial killer.