We speak with experts about how conditions, like environment and temperature, affect forensic evidence when a body goes undiscovered for long periods of time.

The Night Stalker, sentenced to death in 1989 for 13 murders, escaped execution when he died of natural causes in 2013.

Although ruled accidental, Elisa Lam's mysterious death at the Cecil Hotel continues to fuel conspiracy theories and speculation.

'A lot of people believe that people who fake their deaths are dummies. And that's just not true,' says Steven Rambam, a private investigator. 'Faking your [own] death is a full-time job.'