The Merry Widow: a woman arranges the murder of her husband to obtain insurance money. The Bad Cop: a former state trooper to disguise a murder as a suicide.

Police must wait nearly 30 years before advances in DNA technology give them the chance to convict the killer of a young hitchhiker. Philadelphia police wage a 16-year hunt for the man who raped and killed a 10-year-old girl.

Detectives from three different departments in Westchester County, NY team up to track down a serial killer. A man known as the Bus Stop Rapist becomes the lead suspect decades after a woman is found murdered under a hotel bed.

A woman calls police to say that her fiancée killed a California woman in 1993; the 1988 murder of actress Myra Davis.

After 23 years, investigators finally track down the killers of an Atlanta policeman when the ex-wife of one of the killers phones in a tip; and a mother keeps the skeletal remains of the 3-year-old daughter she killed in a footlocker.

Minneapolis police search for a murderer who calls 911 and leaves weepy-voiced confessions.

A woman who takes down the license plate number of a car that had been following her helps police solve the murder of another young woman.

The testimony of three prison inmates helps convict a man who viciously killed a woman out for a bike ride nearly two decades prior; and a self-admitted sex addict who strangled his cat is a suspect in the 30-year-old murder of a neighbor.

Advances in DNA technology help police to finally identify the man who brutally stabbed two women to death; and an anonymous caller leads police to the killer of a 13-year-old girl who was shot dead and left in the woods.

A man is suspected of killing his family by pushing them off a cliff in 1996. A 13-year-old girl is murdered in Seattle in 1982 and DNA on an envelope may lead to her killer.

New York denizen Arohn Kee is a lesser known serial killer, but no less odious. He preyed on teenage girls in Harlem.

A scheme to bribe a country music magazine to manipulate the charts leads to murder in Nashville and a 13-year hunt for the killer. A murderer's plan to hide his gun and ammunition is foiled.

An eerie note left on a grave helps solve a 12-year-old case of murder, and an exhaustive questioning of a mother helps police unravel the mysterious deaths of three of her children.