(CNN) -- Authorities in Cleveland, Ohio, brought in cadaver dogs Wednesday to search the childhood home of a registered sex offender accused in the deaths of 11 women.
"We're just trying to cover all our bases," said Scott Wilson, spokesman for the FBI, which is assisting local detectives in the case.
Anthony Sowell, 50, was arrested in October after authorities serving a search warrant in a rape case discovered six bodies in and around his current home. Subsequent searches turned up five more bodies, all African-American women.
Authorities have said they are looking at the unsolved murders of three women in East Cleveland to determine whether they share any similarities with the remains found at Sowell's home.
Wednesday's search comes a day after Sowell was indicted on 85 counts -- including aggravated murder, rape and kidnapping -- in the killings. In addition, Sowell is charged with "brutalizing" three other women and raping two of them, Cuyahoga County prosecutor Bill Mason said Tuesday.
Prosecutors are seeking the death penalty against Sowell, Mason said. He is scheduled to be arraigned Thursday.
Sowell is now charged with 11 counts of aggravated murder with a "mass murder specification," meaning multiple people were killed in a similar fashion, Mason said. He also is charged with abuse of a corpse, kidnapping and tampering with evidence.
The indictment also alleges that Sowell assaulted women on December 8, 2008, and on September 22 and October 20 of this year. The September and October victims were raped, and the other woman was punched and choked before she escaped, Mason said. Sowell's charges in those incidents include attempted murder, rape or attempted rape, kidnapping, robbery and felonious assault.
Sowell already faced charges in the September 22 rape and has pleaded not guilty.
On October 20, neighbors reported seeing a naked woman fall from the second floor of his house. Firefighters responded and later notified police.
But the woman told officers that she fell off the roof while she was at the home "partying," police said earlier. No charges were filed at the time.
Sowell threatened his victims and warned them not to contact police, Mason said. It's possible there are other victims, he added, and urged anyone who has not come forward to do so.
Sowell "knew what he was doing was wrong at the time he was doing it," the prosecutor said.
As of last month, Sowell was on suicide watch at the request of his public defender, Kathleen DeMetz. She had said a psychiatric evaluation had been ordered but was unlikely to happen until after an indictment was filed.
Cuyahoga County Sheriff Bob Reid said Tuesday that Sowell has been a "model prisoner," is kept in an isolated unit and has declined visitation requests.
Most of the victims were strangled by ligature -- which could include a string, cord or wire -- and at least one was strangled by hand, officials said. Seven still had ligatures wrapped around their necks. All that has been found of one woman is a skull that was wrapped in a paper bag and stuffed into a bucket in the home's basement.
Sowell served 15 years in prison for a 1989 attempted rape and was released in 2005. He was required to register as a sex offender.
After the 11 victims were found, police used thermal imaging in mid-November in an attempt to see whether any additional human remains were on the property, and they dug certain areas by hand. No more were found.