One of the skeletons had a revolver in its right hand.

Homicide detectives are working on the theory that the bones of two people found yesterday in a ranch house in Northeast Philadelphia were the remains of a murder-suicide.

The corner home with overgrown grass on the 10000 block of Bustleton Avenue in Lumar Park belonged to a reclusive retired police officer and his octogenarian mother, for whom he was the caregiver.

One neighbor, among the few who said he knew them, said he had not seen the son since late summer 2005.

Police said they would not release the names until the identities of the remains were confirmed, probably through dental records.

Police Chief Inspector Scott Small said Water Department workers made the grisly discovery when they "gained entry" to the house to shut off the water. It was not clear how they got in, but the Water Department said it had received an anonymous report that water was flowing out of the house.

The floor inside was badly damaged and buckled from flooding, Small said.

The two skeletons were found in a bedroom, one in a bed, the other in a chair.

"The body in the chair had what appears to be a 5-shot revolver in the right hand," Small said.

They were so decomposed it will take an expert to determine the sexes of the skeletons, he said.

Police found a note, but Small would not disclose its contents or whether it was dated.

He said neighbors told police they had not seen the residents of the house for more than a year, during which time the city had mowed that lawn under the Clips program.

Investigators will check to see whether police were called to check on the well-being of the pair, the chief inspector said.

The house, surrounded by hedges and off the street, was "pretty sealed up," Small said, explaining why neighbors may not have detected an odor.

One neighbor who would only give his name Rob said the retired officer was in his 50s and cared for his ailing mother.

"He didn't seem to have any friends," the neighbor said. "He stayed by himself. . . . He would not put her in a home."

Caregiver stress has been cited as a factor in a possible cause in a number of murder-suicides around the country in the past decade.

Contact staff writer Joseph Gambardello at 215-854-2153 or jgambardello@phillynews.com.