18-year-old James Paine entered his plea in Somerset superior court Thursday.
Back in November of 2007, he was indicted by a grand jury and arrested.
Police say Paine was driving on Parkman Hill Road in Skowhegan in August of 2007, when he lost control of his car, hitting 87-year-old Bernard Currier, who was on a riding lawnmower at the time.
Currier was killed in the collision.
Police say speed appeared to have played a role in the crash.
Paine is being held at the Somerset county jail on a $25,000 bail.