A regional leader of Brazil's landless farmers' movement was found murdered.
The body of Valdecir Padilha, 31, was found on a roadside near the Paraguayan border, police say.
The landless movement leads large-scale occupations of land it considers unproductive.
Police in Navirai, 900 kilometres (540 miles) west of Sao Paulo, say the body was found in the neighbouring municipality of Itaquirai on Saturday morning.
Local news agency Agencia Estado reported that Padilha's body had been found on a roadside with three gunshot wounds in the chest and one in the neck.
Padilha was doing community service at Itaquirai hospital as a sentence for leading several invasions of large farms and ranches for the Landless Farmworkers Movement.
In recent years, the landless movement has also taken to invading banks and other public institutions to press its demands, which include the settlement of some 4 million landless families it claims to represent.
In Brazil, the richest 20% of the population own about 90% of the land, while the poorest 40% hold just 1%.
More than 1,000 Brazilians have lost their lives in land disputes over the past decade, according to the Land Pastoral, a Roman Catholic group that advocates land reform.