Indigenous activist Leonard Peltier, who has spent most of his life in prison since his conviction in the 1975 killings of two FBI agents in South Dakota, has a parole hearing Monday at a federal prison in Florida.

At 79, his health is failing, and if this parole request is denied, it might be a decade or more before it is considered again, said his attorney Kevin Sharp, a former federal judge. Sharp and other supporters have long argued that Peltier was wrongly convicted and say now that this effort may be his last chance at freedom.

“This whole entire hearing is a battle for his life,” said Nick Tilsen, president and CEO of the NDN Collective, an Indigenous-led advocacy group. “It’s time for him to come home.”

The FBI and its current and former agents dispute the claims of innocence. The fight for Peltier’s freedom, which is embroiled in the Indigenous rights movements, remains so robust nearly half a century later that “Free Peltier” T-shirts and caps are still hawked online.