A mentally retarded man told a judge Friday he raped and killed five women and a teenage girl more than a decade ago, prosecutors said.

As part of an agreement with prosecutors, Eugene Britt, 48, pleaded guilty but mentally ill to only three murders. Lake County prosecutors said Britt would be sentenced to 245 years in prison.

Last week, the judge ruled he was mentally retarded and could not get the death penalty.

Defense attorney Gojko Kasich said his client has injuries suffered from being hit by a train during a 1995 suicide attempt after the killings.

Britt already is serving life in prison plus 100 years for the 1995 slaying of an 8-year-old girl.

"It was the best resolution under the circumstances," Kasich said of the plea deal. "We never indicated a desire (for Britt) to get out, and he believed he should remain in an institution."

Prosecutors say Britt attacked the women from behind, usually grabbing them by the neck, dragging them to abandoned locations and raping them. In a 1995 confession to police, he admitted to nine killings, but no charges were ever filed in two of the cases.