A Harvard Extension School student pleaded not guilty to charges of motor vehicle homicide and leaving the scene of an accident during his arraignment Tuesday in Somerville District Court.

Ricardo J. Sansone, a Venezuelan citizen, was released on personal recognizance after pleading not guilty to allegedly hitting Thomas F. Kennedy Jr., a Brookline resident, on Rte. 1-93 in Andover early Monday morning. Assistant District Attorney Charles M. Hughes said yesterday.

The pretrial hearing will take place in Summerville District Court on April 2.

The 28-year-old Kennedy was instantly killed when struck by Sansone's 1983 Buick. Two hours after the accident. Sansone turned himself in to Medford police and admitted to hitting the man, state trooper John J. Malone said.