A US judge has ordered release of a man who has spent 43 years in solitary confinement for a crime he denied committing, a media report said.

US District Judge James J. Brady  ruled that Albert Woodfox, 68, should be released from prison and should not face a third trial due to “exceptional circumstances”, including his age and poor health and the court’s “lack of confidence in the state to provide a fair third trial”, CNN reported.

Woodfox is the last imprisoned member of the “Angola 3”, a group of prisoners who were accused in the 1972 killing of guard Brent Miller at the Louisiana State Penitentiary in Angola.

Woodfox, who was originally imprisoned on an armed robbery conviction, has said that he had tried to point out injustices at the prison and was targeted and wrongfully accused because of his activism.

Robert King, another one of the “Angola 3”, was freed after his conviction in the killing of a fellow inmate was overturned in 2001.

The second member of the group, Herman Wallace was released in 2013 after a judge vacated his murder conviction and sentence. He was suffering from terminal liver cancer and died just days later after his release.

A federal appeals court overturned Woodfox’s conviction last year.

However, the Louisiana Attorney General’s Office is seeking an emergency stay to block the judge’s decision, and said “make sure this murderer stays in prison and remains fully accountable for his actions”.

Amnesty International praised the decision as a big step toward justice.