SAO PAULO (AP) – An indigenous leader who fought for the demarcation of his tribe’s ancestral lands has been stabbed to death, apparently by his father-in-law, police said Tuesday.

Ambrosio Vilhalva, a leader of Brazil’s Guarani-Kaiowa tribe, was attacked Sunday night as he approached his house in central-western Brazil, said Benjamin Law, police inspector in the town of Caarapo, in Mato Grosso do Sul state.

Vilhalva starred in the 2008 film “Birdwatchers” about his tribe’s struggle to return to its ancestral lands.

 Law said by telephone that Vilhalva “stumbled into his home and just before dying he told his wife who his killer was.” Police arrested the father-in-law, Ricardo Mendes Quevedo, who has denied killing Vilhalva.

The police inspector said he did not know of a motive in the killing but doubted it was related to Vilhalva’s efforts for the demarcation of Indian territory.

Thousands of Guarani-Kaiowa Indians have lived in Mato Grosso do Sul state for years in makeshift camps along highways and tent villages by rivers while lobbying to have their lands legally recognized.

According to the Brazil-based indigenous rights group CIMI, 319 Guarani-Kaiowa Indians were slain from 2003-2012, mostly of them in fights over land with farmers and ranchers encroaching on their land. That’s more than half of all 558 Indians killed in the entire country during the same period.