(CNN) -- Six women found dead at a Cleveland, Ohio, home appeared to have been strangled, and their decomposing bodies could have been lying there for "weeks, if not months or years," a coroner told CNN on Saturday.
Police discovered the bodies at the home of Anthony Sowell, a 50-year-old sex offender, after they tried to serve an arrest and search warrant for him related to a sexual assault investigation.
On Thursday, detectives from the department's sex-crimes unit and members of its SWAT team went to Sowell's home to execute the warrant and to arrest the suspect, but he was nowhere to be found, Cleveland Police spokesman Lt. Thomas Stacho said.
Five female victims were found inside the home, and another female body was discovered outside the home, said Cuyahoga County Coroner Frank Miller III.
Miller's office had yet to identify the victims, who all died of "homicidal violence," he said.
"They were mostly strangled, it appears," he said.
Stacho said a tipster told officers of Sowell's whereabouts and police arrested him Saturday afternoon as he walked on a street near the 4th District Police Headquarters.
About a month ago, a woman accused Sowell of rape and felonious assault, Stacho said Friday.
"Once we were able to get the cooperation of the victim, we secured an arrest warrant for Mr. Sowell and subsequently a search warrant for his premises," Stacho said.
Officers serving the warrants Thursday discovered two badly decomposed bodies on the third floor of the house, Stacho said. A subsequent search revealed what appeared to be a freshly dug grave under the stairs in the basement, he said.
On Friday, investigators returned to the house, dug up the grave and found a third body, he said.
A further search of the house and property found two more bodies in a crawl space, and a sixth body was found in a shallow grave outside the home, Stacho said.
Five different burial methods were used on the victims, and the bodies were in varying states of decomposition, Miller said, making it difficult to determine the ages of the victims. He added that the states of the bodies made it hard to tell how long they had lain in the makeshift graves.
"It's really very difficult to tell," Miller said. "It's been some time, I would say probably at least weeks, if not months or years."
Stacho said Sowell makes his living as a "scrapper."
"He walks around and picks up scrap metal and takes it to junkyards to make a few pennies."
Sowell pleaded guilty to attempted rape in a 1989 case for which he was imprisoned from 1990 to 2005, Stacho said.
CNN's John Branch and Barbara Hall contributed to this report.