BALTIMORE, MD - The parents of a prison inmate killed last year aboard a prison bus are suing the state for negligence.

The lawsuit filed yesterday by Melissa Rodriguez and Philip Parker seeks 51 million dollars in damages.

Twenty-year-old Philip Parker Junior was strangled in February 2005 as the bus traveled from Hagerstown to Baltimore. Another inmate, 23-year-old Kevin Johns, was charged with first-degree murder.

The suit alleges the driver and four officers aboard the bus were inattentive or unwilling to intervene in the struggle. According to the suit, the officers were sleeping, listening to a radio or watching a portable television. And Parker's parents claim that lighting on the bus was broken.