An investigation into the 2002 murders of Karen Harkness and Michael Sisco in Topeka, Kan. The couple were shot to death in Harkness' home.

An unfaithful husband is killed.

The 2009 death of Air Force veteran Brittney Brashers is investigated in Colorado. Brashers was found dead following a car accident with her boyfriend, Robert Walters, but authorities became convinced that she didn't die as a result of the wreck. Walters survived the accident.

The 2009 death of former adult actress Felicia Tang is investigated. Her boyfriend, Brian Randone, a one-time youth minister, is the lead suspect in the case.

The 2007 death of Eleonora Kaufman is investigated. Her husband, Adam Kaufman, is the chief suspect in the case.

The brutal 2010 murder of Washington state teen Mackenzie Cowell is investigated. The 17-year-old beauty-school student was found beaten and strangled along the Columbia River.

The murders and disappearances of at least 18 women along British Columbia's Highway 16, known as the "Highway of Tears," are investigated.

The 1984 murder of Jay French in South Pasadena is investigated. Frank O'Connell was found guilty of the crime in 1985; he was released from prison in 2012 after his conviction was overturned and the case against him was dismissed.

The hunt for convicted killer George Wright, who murdered war hero Walter Patterson in 1962 and then escaped from a New Jersey prison in 1970.

The 2009 murder of Dana Edwards in San Antonio is investigated. Her ex-boyfriend, Jon Thomas Ford, is the chief suspect and is tormented by the victim's mother, who believes he is guilty.