Former colleagues of accused Gilgo Beach serial killer reveal what it was like working with him

People who used to work with the man accused of the Gilgo Beach murders have described what he was like when they knew him as a colleague.

Rex Heuermann has been accused of killing Melissa Barthlemey, Megan Waterman and Amber Lynn Costello more than a decade ago, before burying them in Gilgo Beach, Long Island.

The three women's bodies were among nearly a dozen sets of remains found on Long Island’s South Shore between 2010 and 2011, with Heuermann also considered a suspect in the death of a fourth woman, Maureen Brainard-Barnes.

Heuermann, who worked as an architect for decades in New York City, pleaded not guilty to the murders following his arrest in July.

He is now the subject of a special Dateline episode set to air today (10 November), which features interviews with those who used to work with him in New York.

In a clip from the episode shared with the New York Post, luxury real estate salesman Jeffrey St. Arromand described Heuermann as being 'very assertive, maybe even leaning to the point of being aggressive'.

Suffolk County Sheriff's Office

St. Arromand worked with Heuermann on preparing a house for sale, and recalled that another woman who was involved in the project 'just didn’t feel comfortable with him at all'.

“She was like, ‘I do not wanna be in the office when he comes and picks up the check,'” St. Arromand told Dateline's Andrea Canning.

He added that working with the architect 'wasn't easy at all'.

Another of Heuermann's former colleagues, Mary Shell, told the show: “You feel afraid … of the world."

“And also, there’s an element of anger. The idea that, as a woman, you have to be suspicious and be afraid all the time just to stay alive is enraging.”

Heuermann’s attorney, Michael Brown, remained confident that his client was innocent after attending a short status hearing in the case in September.

Dateline NBC

Insisting Heuermann was not involved in the murders, Brown said: “He’s a fellow who was working, has never been arrested, has a wife and children, is a productive member of society and, obviously, the district attorney and the government is making these allegations and they’re horrific.

“He’s not guilty of this. Now, he has to sit in custody, be away from his family, be away from his wife and kids, not work, not produce for his family and support them and sit in a jail cell until this case comes to fruition.”

The next court date in the Gilgo Beach case is set for 15 November.

Dateline: The Hunt for the Gilgo Beach Killer is set to air at 9pm ET.