The man who ambushed a police barracks in 2014 only wanted to tell investigators where he had buried the rifles involved in the shooting, and never wanted to talk about any of the alleged crimes.

U.S. marshals, however, continued to press the man on the attack that left one officer dead, and eventually Eric Frein confessed. On Thursday, Frein’s attorney argued before the Pennsylvania Supreme Court that continuing to question his client about the ambush was a severe violation of Frein’s rights under Miranda v. Arizona, which warrants a new trial.