Muhammad, 45, was sentenced to death in a Virginia court in 2004 for one of the 10 shooting deaths during the three-week spree that terrorized the Washington-Baltimore region in 2002.
Muhammad's accomplice, Lee Boyd Malvo, 21, is scheduled to be tried on six murder charges in Montgomery County in October. Muhammad is to be tried in May.
Malvo, who was 17 at the time of the killings, is not eligible for the death penalty because he was a minor when the crimes were committed.
Gansler said his office filed the papers seeking a sentence of life without the possibility of parole early last month.
Paul DeWolfe, Muhammad's attorney, could not be reached for comment late last night. But in a September interview with The Sun, DeWolfe said he did not think Muhammad was eligible for the death penalty under Maryland law.
Gansler said he decided against seeking the death sentence for Muhammad partly to relieve taxpayers of the burden of a protracted, costly trial. But he also acknowledged the challenge prosecutors would face in trying to persuade a Maryland jury to impose the death sentence.