Lee Boyd Malvo en route to pre-trial
Sniper suspect Lee Malvo (c) leaves a pre-trial hearing at the Fairfax County Juvenile and Domestic Relations Court Dec. 4th, 2002 in Fairfax, Virginia. LUKE FRAZZA/AFP/Getty Images

Nearly 15 years after Lee Boyd Malvo was sentenced to life in prison for his role in the 2002 Beltway Sniper Attacks, the Supreme Court agreed Monday to review a lower court order for a new sentencing hearing.

Malvo was 17 years old when he and John Allen Muhammad embarked on a series of shootings in the D.C.-area over a three-week period that left 10 dead and six wounded.

Muhammad received the death penalty and in 2009 was executed by lethal injection, while Malvo received four sentences of life without parole in Virginia and six in Maryland.

Since then, Malvo has disputed his sentencing in Virginia because he was a minor, citing a 2012 ruling by the Supreme Court which obligated mandatory life sentences for juveniles like Malvo's to be struck down — a ruling that was declared retroactive in 2016.

A ruling in June made by the 4th U.S. Circuit Court of Appeals also upheld the decision made by the Supreme Court in 2012, stating that while Malvo's sentence was within jurisprudence, the precedents set by other sentencing rulings for juveniles ultimately impacted the fairness of his life sentence.

An appeals court judge stated that re-sentencing Malvo would require the courts to decide whether he is "one of the rare juvenile offenders" who can be sentenced to life without parole due to "crimes [that] reflect permanent incorrigibility," rather than "the transient immaturity of youth."

A Maryland psychiatrist in 2003 testified that Malvo was legally insane.

Malvo's defense claimed he had been "indoctrinated" by Muhammad to participate in the killing spree and had been a vulnerable target for Muhammad due to the lack of a father figure in his life.

Another psychiatrist quoted Boyd as saying: "[a]nything [Muhammad] asked me to do I'd do. He knew I didn't have a father. He knew my weaknesses and what was missing."

Malvo stated during a 2012 interview on NBC's "Today" that he had been sexually abused by Muhammad from the age of 15 until the time of his arrest.

Despite the appeal, the convicted spree killer will most likely not experience an early release due to sentences imposed by a Maryland court. Malvo had agreed to a plea deal in Maryland.

The Supreme Court will hear Malvo's re-sentencing case in October.