The Parole Board on Tuesday voted unanimously to award parole to Koonce, a decision that will allow him to return to the community, with some conditions in place, nearly three decades after a Bristol County jury sentenced him to life in prison without parole for murdering Mark Santos.

In its decision, the board said Koonce has “taken responsibility for the death of Mr. Santos and has spent his incarceration working towards his rehabilitation,” describing him as “remorseful and empathetic towards the Santos family and the community.”

“He has had an excellent adjustment and has taken extraordinary steps to improve himself and the lives of other incarcerated individuals including initiating Restorative Justice and continuing involvement in the Second Thoughts Program,” the board, which is chaired by Gloriann Moroney, wrote. “He has been a mentor and facilitator to many in the incarcerated population. Mr. Koonce’s self-development has also included achieving a bachelor’s degree and vocational skills. Much of his rehabilitative work occurred prior to any opportunity for parole.”

When he leaves MCI-Norfolk, Koonce will be required to go to the Criminal Resources for Justice program at Boston’s Brooke House, a transitional residential home for men departing incarceration, for four months as a condition of his parole.

He will then be released to an approved family-sponsored or independent living home plan, where he will be subject to electronic monitoring, supervised to ensure he abstains from drugs and alcohol, expected to comply with a substance abuse evaluation plan, and required to remain home between 10 p.m. and 6 a.m.

Koonce will not be permitted to have any contact with the victim’s family, which has previously opposed his push for release. He must also participate in counseling to help him adjust to life outside prison.

In 1987, during an altercation between groups of people from New Bedford and Brockton, Koonce fired a gun out of a vehicle window, striking and killing the 24-year-old Santos.

Koonce, a U.S. Marine veteran, rejected a proposed deal with prosecutors to plead guilty to manslaughter, which would have carried a maximum sentence of 10 years in prison. A Bristol Superior Court in 1992 sentenced him to first-degree murder and life in prison without parole.

At his commutation hearing in January, Koonce, now 55, opened his remarks by apologizing to the Santos family, saying he knows their lives “will never be the same.”

“I take full responsibility for taking his life,” Koonce said of Santos. “My life will be forever dedicated to giving back to society.”

The Santos family unsuccessfully urged the Governor’s Council to reject a push to reduce Koonce’s sentence, likening their suffering in the wake of Mark’s murder to a life sentence.

“If Koonce’s sentence is shortened, what board should we go to for our sentence reduction?” the Santos parents wrote to the panel. “Our family is asking your honor not to renege on a promise the state of Massachusetts made to our family in 1992. It was the promise of life in prison without a chance at parole that ensured our family that we deserved justice for our loved one.”

Koonce became eligible to seek release on parole after earning support for a commutation bid he launched in 2014. Following the Parole Board’s recommendation, Gov. Charlie Baker in January announced he wanted to reduce the sentences of Koonce and 48-year-old William Allen to second-degree murder, which would allow them to petition for parole.

The Governor’s Council on Feb. 16 unanimously approved both commutation petitions, representing the first time since 1997 that the elected panel commuted a first-degree murder sentence and only the second time in the past 25 years that it awarded any commutation at all.

“I just want to be clear that I think that both of these men should have been convicted,” Councilor Terry Kennedy of Lynnfield said at the time of the commutation vote. “They both committed very, very serious crimes and young men died as a result of their actions. … It doesn’t mean that they’re innocent of what they did. And they’ve paid a very high price for what they did. But I think they’ve both paid enough.”