The suspect in the Gilgo Beach serial killings had a stash of more than 200 guns in a vault inside his home, the Suffolk County Police Commissioner said.

Investigators are still trying to determine if the guns belonging to Rex Heuermann, 59, are legally registered, Commissioner Rodney Harrison and friendsin an interview on Monday.

“He had an armory in a vault downstairs,” he said.

«Any time someone has that kind of arsenal, we have some concerns,» Harrison added.

A police spokesman said they will not «disclose anything more about the seized items/evidence.»

Suffolk County District Attorney Ray Tierney told ABC News police arrested Heuermann, a married New York architect, at his midtown Manhattan office Thursday night because of the stash.

«We wanted to detain him somewhere outside the house, for access to those weapons,» he said.

Heuermann was charged Friday with three counts of first-degree murder and three counts of second-degree murder in the death of 24-year-old Melissa Barthelemy; Megan Waterman, 22; and Amber Lynn Costello 27.

The remains of the women were discovered in December 2010 in Gilgo Beach on the south shore of Long Island, and they were all believed to be sex workers advertising on online sites, according to police.

Heuermann is also a suspect in the disappearance and death of a fourth woman, 25-year-old Maureen Brainard-Barnes, whose remains were also found near Gilgo Beach. That investigation is still ongoing, according to a bond request.

Michael J. Brown, Heuermann’s attorney, told reporters that his client has denied any involvement, saying the allegations are «extremely circumstantial in nature.»

From left, Melissa Barthelemy, Maureen Brainard-Barnes, Megan Waterman, and Amber Lynn Costello. Rex Heuermann is charged with the murders of Barthelemy, Waterman, and Costello and is a suspect in the disappearance and death of Brainard-Barnes.Suffolk County Police Department via AP file

«All she said, as she cried, was ‘I didn’t do this,'» Brown said. «He’s distraught. He’s clearly distraught about the charges here.»

Heuermann is being held without bail. He has pleaded not guilty.

The remains of the four women, known as the «Gilgo Four,» were discovered during the search for the missing Shannan Gilbert, a 23-year-old who was reportedly last seen running through the gated community of Oak Beach. after leaving a client’s home. according to a policeman case timeline.

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During Gilbert’s search, several other sets of human remains were discovered. In March 2011, the partial remains of Jessica Taylor were found by Suffolk Police along Ocean Parkway in Suffolk County. Eight years earlier, remains belonging to Taylor were also found in Manorville, police said.

On April 4, 2011, three more sets of remains were found on Ocean Parkway in Suffolk County belonging to 24-year-old Valerie Mack, a little girl and a man, police said. A week later, in neighboring Nassau County, where Heuermann lives, two additional sets of remains belonging to the toddler’s mother and an unidentified person were found.

Gilbert’s remains were not found until December 2011.

Heuermann is not suspected in all of the deaths, but he was connected to three of the victims through cellphone data. DNA taken from the discarded pizza also allegedly tied it to a male hair found on burlap used to wrap Waterman, investigators said.

daniella silva contributed.