Gilgo Beach murders: Police dig up suspect's backyard as search for evidence continues

Police are digging up the Gilgo Beach, New York, murder suspect's backyard as the search for evidence continues.

A backhoe was brought to Rex Heuermann's suburban Massapequa Park, Long Island, home on Sunday. The excavating equipment was in use for about three hours on Sunday and remains at the scene.

Suffolk County Police Commissioner Rodney Harrison said Saturday that the search would likely wrap up this week.

One theory investigators are exploring is whether Heuermann, a husband and father of two, killed any of his alleged victims inside his house, but law enforcement sources told ABC News they are still searching for the evidence.

Prosecutors have said that, based on phone records, Heuermann's wife and children were not home at the time of the killings. The records also point to the house as a location where phones pinged, but prosecutors were careful not to identify a location yet where they believe the victims died.

Heuermann, a New York City architect, 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.

He 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.