Amanda Antoni's husband finds her body in their basement with blood everywhere. The scene confounds police: Was it foul play — or a tragic accident?

Sigrid Stevenson's chilling murder on the stage of a locked campus theater still haunts a New Jersey college as new theories about her killer emerge.

After a teen finds an embalmed head in the woods, investigators uncover a possible connection to a black-market organ trade as they try to ID the victim.

Two friends were shot dead at a busy park on a June day, but the killer escaped unseen. Grieving families are on a hunt for clues about the brazen crime.

For decades, a wave of cattle mutilations executed with near-surgical precision has plagued the US. Are extraterrestrials behind these gruesome acts?

Amid eerie sightings of a tall, winged humanoid creature with red eyes, paranormal investigators explore the Mothman's seeming link to major disasters.

Paranormal researcher Don has an odd co-worker: an entity named Becky. A parapsychologist observes Don and Becky at work and is stunned by his findings.

In 1947, an unidentified flying object crashed near Roswell, NM. Was it a spy balloon or an alien encounter? UFO experts unravel the iconic mystery.

London, 1888. The city is gripped by a string of murders, each more gruesome than the last. Experts delve into one of history's most notorious mysteries.