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.

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?

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.

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.

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

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.

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.

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

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.