SANTIAGO, Chile (AP) — A Chilean doctor said Tuesday that a Mapuche indigenous leader sentenced to prison for the arson murders of an elderly couple is now at risk of death due to a long hunger strike.

Celestino Cordova was sentenced to 18 years in prison in 2014 for the attack that killed Werner Luchsinger and his wife Vivian MacKay a year earlier. The couple died while trying to defend their property from hooded trespassers. The crime prompted a national debate about Chile’s struggle to manage violent disputes over ancestral indigenous lands.

Cordova is being held at a jail in the city of Temuco, about 430 miles (700 kilometers) south of the Chilean capital. He has been on a hunger strike for 80 days, demanding to be temporarily released from prison to carry out a religious ritual.

“There’s an imminent vital risk after 80 days without feeding himself,” Cordova’s doctor, Nelson Reyes, said. Cordova’s health could also prompt intervention by President Sebastian Pinera. During his 2010-2014 administration, Pinera faced several hunger strikes by prisoners, but he didn’t cede to their demands.

Prosecutors said hooded men entered the couple’s ranch the night of Jan. 4, 2013, scattering pamphlets on the anniversary of the killing of a young Mapuche activist who had been shot in the back by a police officer just down the road.

Luchsinger fired a shot at one of the trespassers while Mackay desperately telephoned one of her sons. The attackers scattered after torching the house, and the couple died in the flames before help arrived.

Cordova was arrested that night as he ran from the scene, covered in mud, suffering from a gun wound and holding a bloody rag. He denies any wrongdoing.

Most of the Mapuche live in peace in southern Chile. But a radical faction has occupied and burned farms and lumber trucks to demand the return of land taken or sold out from under them as recently as a century ago. Police have responded with force, storming into Mapuche homes during raids and shooting rubber bullets and tear gas at women and children.