Police continue to investigate the murder of four homeless men who were killed in their sleep in Chinatown over the weekend.

Police are looking into suspect Randy Santos' Belmont address for clues to a motive.

The dilapidated three-story house at 691 East 183rd St. is right across the street from an elementary school. Residents say they have called 311 about the constant flow of squatters at the run-down property.

Residents say Santos, a neighborhood homeless man, often stayed at the property. Police say he is being accused of beating four homeless men to death in their sleep.

Police say Santos left a fifth man in critical condition. Prior to the attacks, neighbors described Santos as calm and friendly.

They say he had not been himself lately.

Santos is charged with murder and attempted murder. City records show that the foreclosed property belongs to the Federal National Mortgage Association.

The Buildings Department tells News 12 that the last inspection on the site was back in December of last year. They say the inspection was to investigate a complaint that the property was open and being used by squatters.

Since then, the DOB says it hasn't received a 311 complaint about the property for over a year.

Neighbors tell News 12 the property has been a blight on the block for as long as they can remember.