TOLEDO, Ohio (AP) — An Ohio inmate who admitted taking part in three slayings with his brother in a killing spree that left nine dead during the 1970s and ’80s could soon be released.

The Blade of Toledo reports attorneys for 59-year-old Nathaniel Cook are expected to file for his judicial release as early as this week under terms of his plea agreement.

Cook pleaded guilty to attempted murder and two counts of kidnapping, for a 20-year sentence that ends Tuesday.

Prosecutors say Cook was with his older brother and helped him with three of the nine killings. Anthony Cook is serving two life terms in prison.

The Lucas County prosecutor’s office wants Nathaniel Cook to be evaluated for a possible designation as a sexual predator so he’ll be forced to register his address.