Abdulhakim Muhammad told The Associated Press Tuesday in Little Rock that he confessed to police that he killed Pvt. William Long outside an Army-Navy recruiting center.
But he said murder exists only "without a justified reason."
In a collect call from jail, the 23-year-old man said he didn't specifically plan the June 1 shootings but that they had been on his mind for awhile.
He disputed his lawyer's claim that he had been "radicalized" in a prison in Yemen.