FORT CARSON, Colo.-- A judge has accepted a mentally ill U.S. soldier's guilty plea in the death of a suspected Taliban member who was asleep in a jail cell at a U.S. outpost in Afghanistan.

Pfc. David Lawrence pleaded guilty to premeditated murder Wednesday before Col. Mark Bridges in a military court at Fort Carson in Colorado. The judge later accepted the plea and scheduled sentencing for later in the day.

Lawrence calmly told the judge he fatally shot the suspected Afghan commander because Lawrence's chaplain had been killed by insurgents. Lawrence says he was mentally ill at the time but that didn't prevent him from knowing right from wrong.

Lawrence says he didn't know if the suspected Taliban member killed the chaplain, but he held him responsible because he believed the detainee was a Taliban commander.

Army doctors concluded in January that Lawrence had schizophrenia and post-traumatic stress disorder at the time of the shooting.