Investigators uncover a series of graves while searching for Shannan Gilbert. The hunt for an elusive serial killer begins.
Where's Shannan?
Before disappearing into the darkness of a private oceanfront community, Shannan Gilbert frantically calls 911, leading to a police search and a grisly discovery.
End of the Road
Authorities turn to new technology to unlock DNA secrets stored in a crime lab for a decade.
Cause of Death
Police make yet another series of gruesome discoveries and an autopsy by famed forensic pathologist Dr. Michael Baden challenges the official theory of the Shannon Gilbert case.
Killer Taunts
The killer taunts the sister of one of his victims, providing new leads for investigators.
Grim Tide: Hunting The Long Island Serial Killer Clips
Preview: Grim Tide: Hunting The Long Island Serial Killer
Hosted by senior correspondent Laura Ingle, 'Grim Tide: Hunting The Long Island Serial Killer' examines the unsolved murder mystery of the more than 10 people, many of them sex workers, found on Long Island.
