BUENOS AIRES, Argentina (AP) — Thousands of Argentines are staging a demonstration to demand answers about the fate of a missing activist.

Santiago Maldonado was last seen Aug. 1 when border police evicted a group of indigenous Mapuches from lands in Patagonia owned by Italian clothing company Benetton.

Demonstrators on Friday gathered in front of the presidential palace asking their government to find the 28-year-old alive.

Maldonado's disappearance has sparked violent protests in recent weeks in Argentina. Human rights groups estimate that about 30,000 people died or were forcibly disappeared during the country's 1976-1983 military dictatorship.

Maldonado's family says border police detained him when he was blocking a road in Chubut province. The protesters were demanding the release of a jailed Mapuche leader who is wanted by Chile. Authorities deny any wrongdoing.