Three men had their throats cut and were nearly decapitated, but police are stumped for lead until they consider Boston Marathon Bomber, Tamerlan Tsarnaev, as a suspect.
Lori Vallow's marriage to Chad Daybell seemed like a match made in heaven until her children went missing and her involvement in a cult caught widespread media attention.
Kris Kremers and Lisanne Froon, went missing while hiking in Panama. After a police search, some body parts were located, but no one could determine the causes of death.
Amy Bradley disappeared while on a cruise ship with her family. With no suspects and no help from crew members, her parents contact the FBI to launch an investigation.
Marion Brubaker is mysteriously found dead by a teenager in the neighborhood, but suspicion intensifies when some believe that the teen might have committed the murder.