Suffolk Police Commissioner Rodney Harrison revealed Monday that investigators took numerous items from Rex Heuermann's Massapequa Park home.

Heuermann has been charged with first- and second-degree murder in connection to three Gilgo victims: Melissa Barthelemy, Megan Waterman and Amber Costello. He's the prime suspect in a fourth death. He pleaded not guilty last week and is due back in court Aug. 1.

Reports had emerged that there was a soundproof room discovered, however, Harrison says there is no such room. He says there's only a vault where investigators say Heuermann secured numerous amounts of guns.

Harrison couldn't confirm if any of the victims were ever inside the home. He said investigators are going into every single crevice to make sure nothing is missed.

The commissioner explained that a backhoe and ground penetrating radar are being used and will help them to identify anything in the backyard that they need to take into their possession.

Harrison says there was nothing that prompted the search specifically into the backyard.

"We are doing a total investigation around the house to see if there is anything out there that we need to take a closer look at," says Harrison.

Chopper 12 was overhead as the backhoe was digging in the yard. A police K-9 was also used on the property over the weekend.

Neighbors walking near the home on Monday say they still have a lot of questions about Heuermann and the three murders he is accused of committing.

"It's amazing how something like that can go on for so long, and no one really has any clue," says Deanna Morga, of Massapequa Park.

Several sources have confirmed to News 12 that investigators believe that at least one of the suspected murders could have happened at Heuermann's home.

Harrison would not comment on that but said they will continue investigating even when law enforcement leaves the Massapequa Park property.

"We are going to keep the task force together, we will keep it intact and see if there are any other victims on Ocean Parkway or anywhere else throughout Long Island," Harrison says.

LIVE BLOG: Gilgo Beach Murders

The deaths of 11 people whose remains were found in 2010 and 2011 have long stumped investigators. Most of the victims were young women who had been sex workers. Several of the bodies were found near Gilgo Beach.

Suffolk police confirmed last week that investigators are looking into possible connections between Heuermann, and unsolved cases around the nation – including South Carolina, Nevada and Atlantic City, where four women were murdered in 2006.

Harrison says the investigation at the home could wrap as early as Tuesday or as late as the end of the week. Suffolk police will work with Nassau police to see if they need to have a police presence outside of the home after they wrap the investigation.

WATCH: DOCUMENTARY AND BACKGROUND INFORMATION - Gilgo Beach: Unsolved