Albert Woodfox, an inmate who has been in solitary confinement for 43 years, will be unconditionally released, a federal judge in Louisiana has ordered.

Judge James Brady also banned prosecutors from trying Albert Woodfox for a third time.

Albert Woodfox, now 68, has been in solitary confinement since April 18, 1972 after a prison riot that resulted in the death of a guard.

The inmate was tried twice for the guard’s death, but both convictions were later overturned. He denies all the charges.

On June 8, Judge James Brady ordered the unconditional release of Albert Woodfox and barred a third trial, saying it could not be fair.

A spokesman for the Louisiana attorney general said prosecutors would appeal “to make sure this murderer stays in prison and remains fully accountable for his actions”.

Albert Woodfox is one of three men who were held in solitary confinement at the maximum security Louisiana State Penitentiary and known as the Angola Three, as the prison lies next to a former slave plantation called Angola.

The other two men, Robert King and Herman Wallace, were released in 2001 and 2013 respectively. Herman Wallace died soon after his release pending a new trial. Robert King’s conviction was overturned.

Albert Woodfox and Herman Wallace were involved with the Black Panthers, a militant black rights movement formed in 1966 for self-defense against police brutality and racism, which later embraced “revolutionary” struggle as a way of achieving black liberation.

The three men consistently maintained they were imprisoned for crimes they did not commit, with convictions only obtained after blatant mistrials.

Albert Woodfox, Robert King and Herman Wallace have been the focus of a long-running international justice campaign.