MASSAPEQUA PARK, N.Y. (NewsNation) – Authorities found a vault with “numerous” guns at the home of suspected Gilgo Beach serial killer, Rex Heuermann, but said media reports of a “soundproof room” were “misconstrued.”

“There is a vault, there’s no soundproof room,” Suffolk County Police Commissioner Rodney Harrison told reporters Monday.

Investigators in New York have dug up Heuermann’s backyard, who is accused of killing three women in the Gilgo Beach murder investigation.

A yellow excavator that had been seen scooping dirt in the backyard Sunday was still at the house Monday morning. In Associated Press drone footage, a man could also be seen operating a piece of equipment that can be used to scan for buried objects.

Over the weekend, police dismantled a wooden deck at the house.

Investigators with shovels could be seen scraping through the freshly upturned earth in Heuermann’s yard.

Investigators were also using ground-penetrating radars and police dogs to help with the search. Police haven’t commented on what evidence, if any, they’ve found so far.

Heuermann is charged in the killings of three women whose bodies were discovered along Gilgo Beach in 2010. He’s also suspected in the death of a fourth woman whose body was found in the same area. However, he has not been charged in that case, investigators said.

Heuermann’s arrest on July 14 marked a stunning breakthrough in the hunt for a suspected serial killer who had eluded investigators and whose crimes gripped Long Islanders since the bodies of four women — all of them sex workers — were found wrapped in burlap near Gilgo Beach.

Within months, the remains of six other bodies, including a toddler, were discovered elsewhere along the same beach highway. Heuermann has not been accused in any of those cases. Police have said the deaths may be the work of multiple killers.

Heuermann has pleaded not guilty to the charges.

The Associated Press contributed to this report.