INSIDE THE MIND OF A MADMAN

He was an “ogre — a large white male in his mid-40s with dark bushy hair.” That’s how a friend described the last client Amber Costello, who was working as an escort, was believed to have met with before she disappeared near her West Babylon, N.Y., home on Sept. 2, 2010. Three months later, Costello’s remains were found off a desolate stretch of Ocean Parkway near Gilgo Beach, along with the bodies of 10 other sex workers and a toddler — and the hunt for the “Long Island Serial Killer” began.

Thirteen years later, police believe they’ve finally caught the monster. On July 13, authorities arrested 6-foot-4, 270-pound, 59-year-old commercial architect Rex Heuermann and charged him with the murders of three women — Costello, Melissa Barthelemy and Megan Waterman — and announced he is the prime suspect in the death of a fourth, Maureen Brainard-Barnes, based on a mountain of evidence. “Rex Heuermann is a demon that walks among us,” Suffolk County Police Commissioner Rodney Harrison said of the father of two, who pleaded not guilty. “A predator that ruined families.”

SHOCKING EVIDENCE