CINCINNATI — A man who claims he has killed more than 90 women across the country pleaded guilty Friday to murdering four women in Ohio.

Samuel Little appeared via Skype from the California state prison where he's serving multiple life sentences. He admitted in separate hearings that he killed two women in Cincinnati and two in Cleveland.

Little is possibly the most prolific serial killer in U.S. history, surpassing others such as John Wayne Gacy, Ted Bundy and Gary Ridgway, the Green River Killer.

He was convicted in California of three slayings in 2013 and pleaded guilty to another killing last year in Texas.

Authorities have said they've confirmed at least 60 of the 93 slayings he says he committed in 14 states while he crisscrossed the country for decades.

Little admitted to the 1981 murder of 32-year-old Anna Stewart, last seen alive in Cincinnati. Her body was dumped in Grove City, near Columbus. He also confessed to a second Cincinnati murder, of a woman who remains unidentified.

In Cleveland, authorities said Little strangled to death Mary Jo Peyton, 21, in 1984 and Rose Evans, 32, in 1991.

Cuyahoga County Judge John Russo sentenced Little to a minimum of 40 years in prison to be served after the sentences he's received in Texas, California and Cincinnati.

Authorities are still investigating a third possible homicide by Little in the Cleveland area.