ROCKVILLE — An attorney for a man who pleaded guilty in a series of 2002 sniper attacks that terrified the Washington region asked a judge Thursday to grant him a new sentencing hearing.

Citing recent Supreme Court decisions against mandatory life without parole for juveniles, the attorney for Lee Boyd Malvo — who was 17 when he took part in the crimes — said his client should be given a chance to show he could be rehabilitated.

But a Montgomery County prosecutor countered that the six life-without-parole sentences given to Malvo more than a decade ago were legal and fair. He called the serial shootings “the worst criminal act ever perpetrated upon our community.”

The shootings left 10 people dead and three wounded in Maryland, Virginia and Washington. Malvo took part in the attacks with John Allen Muhammad, who was then 41. Muhammad was executed in Virginia in 2009.

Six of the victims were killed in Montgomery County, where Malvo pleaded guilty to six counts of first-degree murder in 2006.

In the years since, the Supreme Court has ruled that juveniles have constitutional protections against extraordinarily long sentences, and that mandatory life without parole is unconstitutional for children. Defense attorney James Johnston told Montgomery County Circuit Judge Robert A. Greenberg that in light of those rulings, Malvo must get a new sentencing hearing.

“The law did not exist in 2006 the way it does today,” said Johnston, who leads the Youth Resentencing Project at the Maryland public defender’s office.

Johnston said under the court decisions, all juveniles should have at least a chance of release, no matter how egregious their offense.

A key point of contention at Thursday’s hearing was whether the Supreme Court rulings apply to cases in Maryland, where judges have discretion in sentencing people convicted of first-degree murder.

That discretion means the Supreme Court rulings do not apply to Malvo’s case, said Assistant State’s Attorney Brian S. Kleinbord. The decisions cited by Johnston — known as Montgomery v. Louisiana and Miller v. Alabama — dealt with cases in which the sentence of life without parole was mandatory.

The hearing in a packed courtroom in Rockville lasted about an hour. Greenberg did not rule Thursday and did not say when he would issue his written opinion.

Throughout the hearing, the judge questioned both sides on their positions. He said at one point that the facts in Malvo’s case are “so much more gruesome and so much more serious” than those in other cases he has reviewed involving juveniles.

Several relatives of the victims attended the proceedings, but left without commenting to the news media.

Malvo, 32, also was convicted in Virginia and is incarcerated at the Red Onion State Prison there. He did not appear at the Rockville hearing, which was held in the same courthouse where he was sentenced in 2006, and where his accomplice Muhammad was tried.

The Malvo case is among a number of challenges to juvenile life-without-parole sentences throughout the state in light of the Supreme Court rulings.

Russell Butler, an attorney and executive director of the Maryland Crime Victims Resource Center, appeared at the hearing and said victims are “traumatized and re-traumatized every time one of these hearings come out.”

“A lot of them didn’t even know until recently about some of these proceedings,” Butler said.

After the court proceedings, Montgomery County State’s Attorney John McCarthy held a news conference in the lobby of the courthouse and called Malvo “the poster child” for why life without parole should be an available sentence for juveniles.

But McCarthy also said that even if Malvo is re-sentenced and gets a chance for parole, it wouldn’t automatically mean he would be released.

In Maryland, the governor has final say on whether a person serving a life sentence may be paroled.

“I don’t know politically anybody that’s going to ever take the risk of releasing Lee Boyd Malvo, one of the D.C. snipers, back into the community, even 20, 40, 50 years from now, in light of what he did,” McCarthy said. “In reality, this may be a distinction without a difference.”

A federal judge in Virginia recently ruled that Malvo’s life sentences in that state must be reconsidered because of the Supreme Court cases. The attorney general there is appealing the decision.

alisonk@baltsun.com

twitter.com/aliknez