Attorney Ian Friedman confirmed the negotiations Friday but wouldn't offer details. He says if a plea for defendant T.J. Lane occurs, it could happen at his next court date Feb. 26.
The 18-year-old Lane is charged in adult court with fatally shooting three students last February at Chardon High School, east of Cleveland.
A judge has ordered psychiatric testing for Lane. Attorneys for both sides want the testing to determine if Lane is competent to stand trial.
Prosecutors say Lane fired 10 shots at a group of students in a cafeteria. He was at the school waiting for a bus to his alternative school.