BUENOS AIRES, Argentina (AP) — The family of an Argentine activist who was found dead more than two months after he went missing during a protest said Friday he was killed by border police.

Santiago Maldonado's body was found last week in southern Chubut province near the location of a protest on Aug. 1, the day he was last seen. Protesters were demanding the release of a jailed Mapuche indigenous leader and the return of lands owned by Italian company Benetton that are claimed by the Mapuche as their ancestral territory.

Witnesses said they saw police beat and detain Maldonado after he and others blocked a road.

Police never confirmed the arrest and have denied wrongdoing. Preliminary tests have not shown evidence of body injuries, while the cause of death has not been determined yet.

But Maldonado's brother, Sergio Maldonado, told reporters Friday that he was forcibly disappeared. He also criticized President Mauricio Macri's government for the handling of the case and demanded the intervention of independent experts.

"Today, 85 days have passed since we're demanding justice for Santiago," he said. "He was found dead. He was murdered. This was a forced disappearance."

The case of the missing 28-year-old artisan and tattoo artist outraged many in Argentina, where thousands of forced disappearances and other human rights abuses were committed during the brutal 1976-1983 military dictatorship. Tens of thousands of people demonstrated, while soccer players and celebrities joined rights activists in a social media campaign to demand the government find him alive.

Members of Maldonado's family and some rights groups question how his body could have been found in an area of the river that they say had been searched before.

"Santiago didn't disappear on a riverbank, but in the context of border police repression," said Mariela Belski, executive director of Amnesty International Argentina. "It doesn't seem real that this is happening in a democracy."