Gilgo Beach murders: Former FBI profiler says investigators ‘probably’ operating on belief of ‘more victims’

A former profiler for the Federal Bureau of Investigation says that investigators are likely operating off of the belief that there are more victims after the Gilgo Beach serial suspect Rex Heuermann was arrested on Thursday night.

Heuermann is charged with six counts of murder: one count of first degree murder and one count of second degree murder for each of the three victims. The victims have been identified as Melissa Barthelemy, Megan Waterman, and Amber Costello.

He pleaded not guilty to all charges during a court hearing on Friday afternoon.

Mary Ellen O’Toole, a former FBI profiler, told Fox News Digital that investigators are “probably operating off of the theory that there likely are more victims out there.”

WATCH: ‘GRIM TIDE’ ON FOX NATION

“So now they’re going back and they’re looking at cases that have been described as unsolved over the years and moving outside of New York State and New York as well,” O’Toole said.

O’Toole said it’s “not likely” Heuermann began acting out in his late-30s.

READ: CASE AGAINST REX HEUERMANN

“It’s more likely these serial sexual killers start to act out, if they’re going to, they start to act out in their early to mid-twenties. So they’re going to go back in time and they’re going to timeline him. They’ll go back to when he was in college and go back beyond,” she said.

WHO IS REX HEUERMANN?

Heuermann is married and has two children, working as an architect in Manhattan while living on Long Island.

“I’m an architect. I’m an architect consultant. I’m a troubleshooter. Born and raised on Long Island. Then working in Manhattan since 1987,” Heuermann said in a February 2022 video interview with Bonjour Realty posted to YouTube. “When a job that should’ve been routine suddenly becomes not routine, I get the phone call.”