Thirteen-year-old Abby Williams and 14-year-old Libby German disappear while hiking on a popular trail; 13-year-old Dylan Redwine vanishes over Thanksgiving break while visiting his father in Vallecito, Colo.

Eighteen-year-old Brookelyn Farthing disappears in 2013 after attending a party in Berea, Ky.; 24-year-old realtor Lindsay Buziak is found brutally killed after showing new clients a million-dollar home.

In Mobile, Ala., young mother Danniella Vian, 25, disappears into thin air; 19-year-old Holly Moore's suspicious death still raises questions four years after her body is found hanging in her closet

A man's trip ends badly. A missing mom's search party sparks suspicion.

A girl vanishes on her way home, and an entrepreneur dies after a fight.

A beer entrepreneur is gunned down, and two friends die while on vacation.

One mom is missing and another spurs a manhunt for her daughter's killer.

When two women die suddenly under mysterious circumstances, authorities initially suspect suicide. But both of their families believe it was murder, and are trying to figure out who is responsible.

Florida insurance agent Carla Stefaniak vanishes in Costa Rica; 19-year-old college student Pravin Varughese disappears after a party in 2014.

A severed foot is an ominous clue in the case of a missing mother of five.

In an ironic twist, a woman vanishes while looking for her missing friend.

After a night out with friends, Jaleayah Davis, 20, is found dead; Kelsie Schelling, 21, drives two hours to show her boyfriend a sonogram of their baby, but never makes it home.

A brazen public stabbing and a house fire snuff out the lives of two women.

A war veteran turns up dead, and a missing man leaves a creepy voicemail.

A man relocates only to be stabbed. A student is found dead in her car.

A mother of two and a young woman planning a career in science both die under mysterious circumstances, and two families embark on quests for justice.

A family suspects foul play when their son drowns in a few inches of water.

He seems like a great partner. But when Susan Osborne and her 14-year-old son Evan disappear, it turns out "Mr. Right" has a secret. Then, when a young man is shot in a street confrontation, all clues point to one man. Could this case be that simple?

The callously dismembered body of a missing woman turns up in trash bags.

The murder-suicide of a mother and son may be something entirely different.

Home becomes the most dangerous place on earth for two lovely young women.

A man and his dog burn to death. A chase ends in murder for a motorist.

A 14-year-old boy vanishes, but neighbors don't tell police what they know.

A young woman on a trip to her father's homeland goes missing, then turns up brutally murdered. Another young mother and her baby are shot as they drive along a highway.

Sisters seek justice for their siblings - but the truth might be deadly.