CLEVELAND — As a registered sex offender, Anthony Sowell checked in regularly with law-enforcement authorities, who also monitored him by making home visits.

But since Sowell wasn't on parole or probation, they didn't have the right to enter — until Thursday when they had search and arrest warrants after a woman said he had raped her there. That's when they discovered badly decomposed bodies in the house.

By Sunday, authorities determined there were six bodies, all of them women, and each was the victim of a homicide.

Officers had last visited Sowell at home as part of his sex-offender monitoring Sept. 22, just hours before the woman reported being raped there.

The three-story house with neat white siding is in a crowded inner-city neighborhood of mostly older houses. The windows on the third floor, where the first two bodies were found, were wide open Sunday as a slight breeze blew. Some neighbors said a bad smell came from the house several months ago, but they thought then it might be natural gas.

At least five of the women apparently had been strangled, said Powell Caesar, a spokesman for the Cuyahoga County coroner. Decomposition made it difficult to determine how the sixth died, he said.

The bodies "could have been there anywhere from weeks to months to years," Caesar said.

None of the victims has been identified. Two were black, but the race of the others hadn't been determined, Caesar said.

Sowell, 50, previously spent 15 years in prison for choking and raping a woman who was lured to his bedroom in 1989, police said. He was arrested Saturday when officers spotted him walking down the street in his neighborhood.

The first bodies were found Thursday night when police went to arrest Sowell on new charges of rape and felonious assault, but he wasn't home. The woman in that alleged attack said she knew Sowell, and he raped her at the house.

Court records and jail officials had no information about whether Sowell had an attorney. No charges have been filed regarding the bodies.

The gruesome discovery left some in the community concerned about women who hadn't been seen in a long time.

Sowell often walked around his neighborhood asking for money and looking for scrap metal to sell, neighbors said. He returned to the family home in 2005 after his release from prison. The house was owned by two of Sowell's relatives, including a woman — described by neighbors as either Sowell's stepmother or aunt — who maintained it.

Neighbors said the woman moved into a nursing home after Sowell was released from prison. Teresa Hicks, a neighbor, said people feared she might be dead. Police were looking into her status.