Despite the decision by a judge to release Albert Woodfox from prison earlier in the week, a federal appeals court ruled Friday that the only remaining "Angola 3" inmate must remain in custody while a decision is made as to whether or not he can be retried, The Associated Press reports.

U.S. District Judge James J. Brady ruled on Monday that Woodfox should not have to face trial for a third time. After the decision was announced, Louisiana Attorney General Buddy Caldwell formally appealed it, saying that "Woodfox is a killer who should remain locked up."

A three-judge panel of the 5th U.S. Circuit Court of Appeals blocked his immediate release, and now Woodfox must wait until the court makes a final decision, according to the AP.

Woodfox has reportedly been in solitary confinement for more than four decades. He is "the prisoner serving the longest time in solitary confinement in the United States," according to The Advocate.

Woodfox is one of three people that were convicted in the 1972 killing of Brent Miller, who was a guard at Louisiana State Penitentiary at Angola. The inmate has consistently pleaded his innocence. At Angola because of a prior armed robbery charge, Woodfox claims he was treated unfairly because he was outspoken against "injustices" at the prison.

His two previous convictions connected to this case were overturned, and the inmate's lawyers successfully argued with Brady that another trial, especially after spending more than four decades in solitary confinement, would be an injustice to Woodfox.

At the time of Miller's killing, inmates were protesting harsh conditions inside the prison.

The two other members of the "Angola 3," a name for the group coined by the numerous people that have protested the inmates' very long stints in solitary confinement, did not fully serve their sentences either.

Robert King was released from prison in 2001. He was serving time for killing a fellow inmate but the conviction was overturned. The other "Angola 3" inmate, Herman Wallace, was freed in 2013. A judge vacated his conviction in the Miller case, in part because Wallace was terminally ill with cancer. He died just days after being released.. 

King and Wallace, like Woodfox, claimed innocence and unfair trials connected to Miller's death.