The Cuyahoga County Medical Examiner's Office confirmed Sunday in a statement the three bodies are female in states of advanced decomposition.
On Saturday, Police Commander Mike Cardilli announced that a woman's body had been found Friday in a garage and two other bodies were found a day later - one in a backyard and the other in the basement of a vacant house.
The bodies were found about 150 yards apart. All three people are believed to have been killed in the last six to 10 days.
Police are questioning Michael Madison, a registered sex offender who appears to have a fascination with convicted serial killer Anthony Sowell.
"He said some things that led us to believe that in some way, shape, or form, Sowell might be an influence," Mayor Gary Norton said.
Sowell is known as The Cleveland Strangler. A jury convicted him in 2011 of killing 11 women and hiding their remains around his Cleveland home. Police found their mostly nude bodies throughout his house after a woman escaped and said she had been raped in there.
East Cleveland police, the FBI and other agencies are searching Madison's neighborhood for additional remains.
The Cleveland area has had its share of gruesome news in recent years. In May, three women who separately vanished a decade ago were found captive in a run-down house. Ariel Castro, a former school bus driver, has been charged with nearly 1,000 counts of kidnap, rape and other crimes. He has pleaded not guilty to all charges.
ABC News and the Associated Press contributed to this report.