Twenty-four-year-old /*Maksim Gelman*/ entered the plea Wednesday in Brooklyn.
Authorities say Gelman's stabbing spree began Feb. 11 after an argument over whether he could use his mother's car. Authorities say it stretched from Brooklyn to Manhattan and included killing his stepfather and acquaintances, running over a pedestrian and carjacking.
Court documents filed earlier this year say the Ukraine-born Gelman told police after his arrest that he expected to beat the charges and spend only a few years in a mental hospital.
His attorney has described his mental state as "fragile."
He had pleaded not guilty to all the charges in April.
