With his final appeal rejected by the Supreme Court on Monday, the mastermind behind the D.C. sniper attacks is scheduled to be executed Tuesday, barring a last-minute commutation of his sentence from Virginia Governor Tim Kaine. John Allen Muhammad, working with his young accomplice Lee Boyd Malvo, killed 10 people in the D.C. metro area in 2002 in a series of sniper attacks that terrorized the populace and garnered national interest. The two were captured on October 24 of that year at a Maryland rest stop. Some relatives of Muhammad's victims plan on watching the execution, while Virginia activist group Virginians for Alternatives to the Death Penalty has planned statewide vigils. Muhammad's lawyers have appealed to Gov. Kaine for a commutation to life in prison on grounds of mental illness.