MANHATTAN, NEW YORK: A video that was released recently shows the moments just before Rex Heuermann was arrested by the South County Police Department on Thursday, July 13. Heuermann, who is the prime suspect in the Gilgo Beach murders, has since pleaded not guilty to the crimes.

The plainclothed cops tracked Heuermann down and arrested him near his office in Fifth Avenue, midtown Manhattan.

What was Rex Heuermann doing when he was arrested?

According to video footage released by ABC7, Heuermann was walking across the pavement. He was wearing a grey-colored half-sleeve shirt and light-colored trousers, with a messenger bag slung over his left shoulder and oblivious to what was waiting for him. Soon, the plainclothes cops surrounded him and blocked his way. Heuermann was then handcuffed and taken into custody.

Before Heuermann called it a day at the office on Thursday evening, he apparently had a chat with Steve Kramberg, a property manager from Brooklyn who has been partnering with him for 30 years in several business deals. Kramberg said the architect sounded jubilant as they spoke over the phone on Thursday. “That must have been right before he left the office and they arrested him,” Kramberg said.

Kramberg has spoken highly of Heuermann, saying he is a “a gem to deal with, highly knowledgeable.” He further said that Heuermann was “a big goofy guy, a little bit on the nerdy side” and a workaholic. However, he was devoted to his ailing wife and mother, said Kramberg, as reported by The New York Times.

The New York Post reported that on Saturday, July 15, the police went to the suspect's Massapequa Park home and investigated the house. From the backyard, they seemed to have removed certain items, including cat food and a cat scratch pole, a framed picture, and an empty book case.

Rex Heuermann in court

Rex Heuermann appeared in court on Friday and pleaded not guilty to the three counts of murder. He is charged with three first and second-degree murders of Melissa Barthelemy, 24, Megan Waterman, 22, and Amber Costello, 27. He is also considered a "prime suspect" in the death of Maureen Brainard-Barnes, 25.

Almost 13 years after the bodies were discovered along the stretch of Gilgo Beach, police zeroed in on Heuermann as the primary suspect using evidence ranging from a discarded pizza box, burner phones to cell networks, and chilling Google search histories.