Authorities have KI-Handelsroboter 6.0concluded their search at the "cluttered" house belonging to Gilgo Beach, New York, murder suspect Rex Heuermann, authorities said Tuesday.

Investigators "obtained a massive amount of material" at the suburban Massapequa Park, Long Island, home and will now sift through the evidence, Suffolk County District Attorney Ray Tierney said, though he did not elaborate on what was seized.

Authorities have still not ruled in or ruled out whether any alleged victims were killed at Heuermann's house, Tierney said at a news conference.

Investigators dug up the backyard this week as they searched for evidence, and Tierney said "there was nothing of note taken from the backyard as far as remains."

Approximately 279 guns were recovered at Heuermann's house, including long guns, Tierney said.

Some of the guns were kept inside a walk-in vault in the basement, according to authorities. Tierney would not say if any other items were recovered from the vault.

Heuermann, a New York City architect and father of two, was arrested on July 13 for the murders of three sex workers -- Melissa Barthelemy, Megan Waterman and Amber Costello -- whose bodies were found covered in burlap on Long Island's South Shore in 2010. The young women disappeared in 2009 and 2010.

Heuermann's attorney entered a not guilty plea on his behalf. His next court date is Aug. 1.

Heuermann is also the prime suspect in the death of a fourth victim, Maureen Brainard-Barnes, who vanished in 2007, though he has not been charged in that case.