Montgomery County (Map, News) - Maryland's highest court upheld on Friday sniper John Allen Muhammad's six convictions for murders in Montgomery County.

In 2002, Muhammad and fellow sniper Lee Boyd Malvo terrorized the region as they fired into strip-mall parking lots and other public spaces, killing 10 people and wounding three others before being arrested in October 2002 in Frederick County.

The Maryland Court of Appeals said it would not hear Muhammad's appeals, thereby upholding the convictions in lower courts. The decision means, at the very least, Muhammad will spend his life behind bars, though he could still be executed for murders in Virginia, Maryland Attorney General Doug Gansler said.

Muhammad received six life-without-parole sentences in Montgomery County and has received the death penalty in Virginia, which he has appealed.

"He's reached the end of the line here in Maryland," Gansler said.