Attorneys for John Allen Muhammad, mastermind of the 2002 sniper attacks in the Washington, D.C., area that left 10 dead, asked the U.S. Supreme Court on Tuesday to stop his execution.

The 48-year-old Muhammad is scheduled to die by injection on Nov. 10 at a Virginia prison. In court papers, his attorneys say the execution should be put off while the court considers whether his trial lawyer was ineffective.

Muhammad was convicted of killing Dean Harold Meyers at a Manassas, Va., gas station during a three-week spree in October 2002 that spanned Maryland, Virginia and the District of Columbia.

Muhammad and his teenage accomplice, Lee Boyd Malvo, were also suspected of fatal shootings in other states, including Louisiana and Alabama. Malvo is serving a life sentence.

Muhammad's lawyers also have asked Virginia Gov. Timothy M. Kaine for clemency, saying Muhammad is mentally ill and should not be executed.