A 40-year-old mother disappears from her home in the middle of the night, and police chase multiple leads before coming up empty. Almost a year goes by until they investigate a very unlikely suspect - a high-school neighbor with an affinity for older women. Then, a teenage boy is murdered in his home and detectives believe his campaign against teen gang activity led to his death. But the community is horrified when police arrest one of their "model citizens" for ordering the hit.

A husband and wife are found shot to death on a deserted stretch of highway. Phone records help detectives uncover a murder-for-hire plot that went horribly wrong, and discover that one of their victims is also their prime suspect. Next, when a 20-year-old woman is found murdered near a freeway exit ramp, the residents of San Diego demand justice. But when a trusted police officer is identified for the crime, the community is shaken to its core.

A young boy is killed in the middle of the night, and his own mother is convicted of the crime. Years later, an author investigates a convicted murderer for her upcoming novel, and gets a confession that re-opens that case file and eventually, sets the mother free.

A delivery man guns down an affluent couple, with their only son barely escaping. The investigation reveals a greedy relative with a motive too close to home. And when a recent victim of burglary is found shot to death in her car, the investigation uncovers a killer the victim trusted without question - the police officer who came to her aide.

A judge and his wife are slain in their home, and the suspects range from common criminals to politicians.

A serial killer on the loose in Spokane prompts investigators to take a new look at an old clue.

A wealthy widow is slain, and the victim's records provide the means to find her killer.

When high-ranking oil executive Sidney Reso is kidnapped, an intensive manhunt turns up few clues. Cryptic letters and phone calls send investigators racing to catch the kidnappers, hoping to bring Reso home alive.

A series of California fires puts investigators on the hunt for a serial arsonist. After years of dogged investigation, an unpopular theory points to a disturbing culprit.

A young couple is gunned down on a lover's lane in Georgia; A husband and wife are shot to death in their suburban Chicago home before the killer sets the house on fire.

In rural Wisconsin, a local eccentric is murdered in his home; A serial killer targets the elderly in Lake Elsinore, California.

Detailing the crimes of serial killer Keith Jesperson, also known as the "Happy Face Killer."

A young woman disappears after a flat tire makes her pull over; a man is murdered while minding his neighbor's property.

In 1996, teenaged Joey Martin sneaks out of his bedroom window to watch a comet from a cabin in the woods-and disappears. Despite multiple leads, there is no sign of Joey until 2008 when a young detective uncovers the shocking story of Joey's fate.

In 1985 when welder Danny Paquette is killed in his front yard by a long-distance rifle shot, there is no shortage of suspects. Many people had issues with Danny. But ultimately the solution falls much closer to home than anyone expected.

When 10-year-old Katie Collman is murdered in a small Indiana town, a shocking confession catapults this crime into national news. Was Katie murdered to keep her quiet about something she saw? An unusual clue leads investigators to the conclusion.

In 2004, affluent Coral Gables couple, John & Susan Sutton, are attacked at home. Susan doesn't survive. Investigators look at an adulterous business partner and an angry client before cell phone records lead to a shooter with ties to the family.

FBI office manager Melissa Mooney is found murdered in her home. After taking a hard look at several promising suspects, the case goes cold. Two years later, a reexamination of the case leads to an unlikely killer who was hiding in plain sight.

In 1984, terrifying screams pierce the Florida night. A day later, a woman's body is found, stabbed to death. Detective Larry Tosi faces a host of suspects, but when the killer is caught, no one will be more shocked than Tosi himself.

"Went 2 Talk 2 Rob" are the last words 15-year-old Becky Stowe writes before she slips out, never to be seen again. Did she run away or did her boyfriend Rob make her disappear? Two years go by before the truth about Becky is finally revealed.

In 1985, an LA County Sheriff is gunned down in his vehicle. Investigators drill down the slain cop's list of enemies with no results. In 1999, a multi-agency task force shines a new light on the old case, illuminating a culprit who defies belief.

When San Diego Police Officer Kirk Johnson is found shot to death in his service vehicle, evidence points to a fellow law enforcement officer. Detectives reluctantly begin to investigate their own when an astonishing tip leads to an unlikely killer.

Soon after Mardi Gras in Mobile, Alabama, an 18-year-old freshman is found shot to death in the woods behind campus. Detectives take a hard look at several suspects, but thirty years go by before a stunning confession cracks the case.

When tycoon Andrew Kissel is stabbed to death in his Greenwich mansion, detectives are faced with a long list of suspects. Practically everyone who knew the victim has a motive for murder. Ultimately, a secret money trail reveals the guilty party.

Season 3 premiere. An attack on a Pennsylvania family that left only one survivor is discussed.