A federal judge on Thursday approved a lighter sentence for a man convicted as a juvenile in the 1994 firebombing that resulted in the deaths of five young St. Paul siblings.

Robert J. Jefferson, a former member of a St. Paul street gang, saw his sentence reduced to 50 years after initially being sent away for life with no chance of parole.

U.S. District Judge Michael Davis’ decision is the first federal sentence to be reduced locally since a 2012 U.S. Supreme Court ruling barred mandatory life sentences for juveniles.

Davis said his ruling “complied with the spirit and the letter of the law” in the Miller vs. Alabama decision, in which the high court ruled that those who committed their crimes before they turned 18 may not automatically be given life sentences.

Jefferson was 16 at the time of the crime.

“I think throughout the whole process here, I conveyed to you through my statements that I’m very remorseful about the things that occurred,” Jefferson told Davis.

Judges have been divided on whether the ruling could be applied retroactively to criminals convicted as juveniles who are already in prison. The Supreme Court is currently considering a case that will decide whether its 2012 decision must be applied to past convictions.

Jefferson’s case wound up in federal court after he and 20 other alleged members of a gang were indicted in 1997 on a charge of operating a drug ring that imported hundreds of thousands of dollars’ worth of cocaine to the Twin Cities from California.

Jefferson was convicted on charges that in February 1994 he and an accomplice hurled Molotov cocktails at the St. Paul home of fellow gang member Andre Coppage in retaliation for cooperating with authorities in a murder case.

Five of Coppage’s siblings — brothers Nicheba, 11, Nicos, 7, and Niarte, 4, and his sisters Nikia, 8, and Myeka, 2 — died in the ensuing fire.

Judge Davis said Jefferson’s upbringing in the gang — his older half-brother, Robert G. “Buster” Jefferson was one of its founders — and reported sexual molestation by an older relative all weighed heavily into his final decision.

The judge said he also considered Jefferson’s good behavior in prison. “I’ve never seen someone not have any infractions in the federal prison,” he said at one point.

Davis added: “And we have to remember you have served more time than you were alive when this … occurred.”

With credit for time served and good behavior, Jefferson could be released in his early 60s, according to prosecutors.

Jefferson has maintained his innocence, despite surveillance camera footage that prosecutors said placed him near the scene of the crime with an accomplice, Willie Hart, shortly after the fire broke out.

Jefferson turned down a plea deal and refused to testify against his half-brother, which prosecutors said was to avoid violating a code of silence.

“You knew what your brother would do to you, didn’t you?” Davis asked.

Jefferson nodded solemnly: “I knew what everybody would do to me, yes.”

Jefferson’s father declined to comment as he and other family members filed out of the 15th-floor courtroom.