T.J. Lane, Chardon High School shooting suspect, pleads guilty to aggravated murder charges

(CBS/AP) CHARDON, Ohio - An Ohio teenager charged with killing three students in a high school cafeteria last year pleaded guilty to aggravated murder charges Tuesday, one day before the anniversary of the deadly shootings.

Pictures:3 killed, 3 injured in Ohio high school shooting

T.J. Lane, 18, pleaded guilty to three counts of aggravated murder, two counts of attempted aggravated murder and a single count of felonious assault. Prosecutors agreed to drop the possibility of the death penalty, and Lane will likely be sentenced to life in prison.

Prosecutors said Lane fired 10 shots at students at Chardon High School, east of Cleveland, on Feb. 27, 2012. Lane, who was 17 at the time, was prosecuted as an adult. Lane attended an alternative school for students who haven't done well in traditional schools. He was at Chardon while waiting for a bus.

Both the defense and the prosecution sought court-ordered psychiatric testing for Lane to determine if he would be competent to stand trial.

Before the case went to adult court last year, a juvenile court judge ruled that Lane was mentally competent despite evidence he suffers from hallucinations, psychosis and fantasies. He withdrew his plea of not guilty by reason of insanity on Tuesday.

Investigators said Lane admitted shooting at students but said he didn't know why he did it. Prosecutors said Lane took a .22-caliber pistol and a knife to the school and fired at a group of students in the cafeteria.

His sentencing is scheduled for March 19.

Complete coverage of T.J. Lane on Crimesider