Sniper John Allen Muhammad refused to utter any last words as he was executed in Virginia.

The 48-year-old took to the grave answers about why and how he plotted the killings of 10 people that terrorized the Washington, D.C., area for three weeks in October 200s.

He died by injection last night as relatives of the victims watched from behind glass at Greenville Correctional Center, south of Richmond.

Muhammad was executed for killing Dean Harold Meyers, who was shot in the head at a Manassas, Va., gas station during the spree across Maryland, Virginia and Washington, D.C.

Muhammad and his teenage accomplice, Lee Boyd Malvo, also were suspected of fatal shootings in states including Louisiana, Alabama and Arizona.