The execution comes seven years after Muhammad and his then-teenage accomplice, Lee Boyd Malvo, frightened people from Baltimore to Richmond with a murder rampage that unfolded day by day.

The snipers killed without apparent plan or purpose, using a high-powered rifle to pick off victims as they went about routine tasks of daily life. Authorities concluded that they hid inside a 1990 Chevrolet Caprice that had been modified into a killing machine, with a hole cut in the back of the trunk for a rifle barrel.

The Jamaican-born Malvo, then 17 and now 24, is serving a sentence of life without parole at a Virginia prison.

Muhammad was sentenced to death for the murder of Dean Harold Meyers, who was shot in the head after refueling his car at a gas station in Manassas, Va., the evening of Oct. 7, 2002.

Maryland Attorney General Douglas F. Gansler called Muhammad's punishment appropriate.

"If you have a death penalty in a state, John Muhammad is the poster child for who should get the death penalty," Gansler said Monday, likening him to Oklahoma City bomber Timothy J. McVeigh, who was executed in 2001 for killing 168 people.

Gansler said Muhammad was effectively being punished for the nine other murders he and Malvo committed while crisscrossing the Washington region.

Six of the murders took place in Montgomery County, three in Virginia and one in Washington. Three other people were shot and wounded, including a 13-year-old boy who had just been dropped off at his Bowie middle school.

Most victims died while doing ordinary activities, such as pumping gas, vacuuming a minivan and sitting on a park bench. The lack of any discernible pattern raised the public's anxiety levels until the pair was arrested at a highway rest stop near Frederick in the early hours of Oct. 24, 2002.

Muhammad and Malvo are suspected of carrying out killings in other states, including Alabama, Louisiana, Arizona and Washington state, beginning in February 2002.

"This was a nationwide murder spree by a serial killer without any motivation other than to wreak terror upon the community," said Gansler, who was Montgomery County state's attorney in 2002. "And he did paralyze an entire community for weeks."

Gansler emphasized the randomness of the killings, which claimed lives from across the demographic and socioeconomic spectrum.

Both Malvo and Muhammad, a former Army marksman, were convicted of murder for the six Montgomery County deaths and sentenced to consecutive life sentences without possibility of parole. Separately, Malvo was convicted of capital murder for one of the Virginia killings but was spared the death penalty.

Gordon, Muhammad's stand-by lawyer in his Maryland case, told reporters outside the prison that his client had "suffered injustices" in the legal system and that reasonable doubt existed that he committed the murders. Gordon also decried the death penalty as "savagery."

Muhammad has been on Virginia's death row since his conviction in 2003 in Meyers' murder. About a month ago he was transferred to the Greensville center in Jarratt, 60 miles south of Richmond, Traylor said.

A large contingent of news media assembled outside the prison hours before the execution. More than a dozen television satellite trucks parked outside the main gate and razor-wire fence. A few hundred yards away, a handful of protesters held anti-death penalty signs. One read: "We remember the victims ... but not with more killing."

Supporters of capital punishment also were present. Pam Clarke, who came with her 13-year-old daughter, Emma Jo, said: "What he did just terrorized so many people. ... An eye for an eye."

Muhammad grew up in Baton Rouge, La., as John Williams and later lived in Tacoma, Wash. His two marriages ended in bitterness, he had run-ins with superiors in the military and he bickered with business partners.

Yet, he could be charming enough to win the confidence of strangers, according to those who knew him. His convincing manner helped him pass off as his son the teenage Malvo, whom he apparently met on the Caribbean island of Antigua.

Even during the sniper saga, Muhammad reportedly showed a chivalrous side chillingly at odds with his murderous behavior.

On Oct. 22, 2002, seven hours after the sniper killed Johnson, a 35-year-old Montgomery County bus driver - their final victim - a tall, well-built black man offered assistance to a woman at a nearby gas station.

"He said, 'Let me pump your gas. You know, there's a sniper on the loose here,' " the woman told The Baltimore Sun in 2002. "I said, 'No thanks, I'm almost finished.' "

Days later she saw photos of Muhammad and Malvo, and realized that it was Muhammad who had offered her the favor. After she declined his offer, he walked back to his car, a Chevy Caprice. Inside sat a boy she later recognized as Malvo, laughing.