Marabá is at the heart of deforestation by ranchers and loggers in the state of Pará. In Nova Ipixuna, near Marabá, there was an attempt to build up a sustainable agro-extractivist reserve (where "extractivism" is used in the sense of Chico Mendes' "extractive reserves"), preserving the castanhais, the chestnut forests of Bertholletia excelsa. On 24 May 2011 José Cláudio Ribeiro da Silva and Maria do Espírito Santo da Silva, who had been leading the Praia Alta Piranheira Extractive Reserve Project, trying to stop land grabbing by outsiders, were ambushed near their home and shot repeatedly. They had received death threats in the past from loggers and cattle ranchers as a result of their work defending the rainforest, and had reported the threats to the police. In November 2010, at an international conference in Manaus, José Cláudio Ribeiros da Silva expressed concern for his own safety  as a result of threats he had received, and predicted that he would be killed as a result of his work.
The bodies of the couple were found inside the Praia Alta-Piranheira reserve, where they had been working for the past 24 years. Environmental and human rights defenders are regularly killed on the frontier of the Amazon, with impunity. These killings occurred at the same time as amendments to the country's forest protection laws were passed in Congress. These amendments were to weaken existing environmental controls and could therefore lead to an intensification of existing disputes. As Felipe Milanez   explained in his doctoral thesis and in blog entries in Carta Capital, one glint of hope in Zé Claudio and Maria’s case for the killers to be brought to justice was the chance that they were murdered the same morning as important revisions to Brazil’s Forest Code were voted in Congress. Their death was announced to the country from the floor of the Congress in Brasilia. The killings took place against a background of ongoing campaigns to silence land rights defenders in Brazil.
According to the Comissão Pastoral da Terra - CPT (Pastoral Land Commission), since 1988, more than 1,150 land and environmental rights defenders, small farmers, judges, priests and other rural workers had been killed in disputes over preserving land. The murders are mostly carried out by gunmen hired by loggers, ranchers and farmers to silence protest over the illegal cutting of trees in the forests. It is reported that fewer than 100 of the cases had gone to court . Both José Caludio and Maria do Espíritu Santo defended the forests of "castanha do Pará", and were implementing Chico Mendes' ideas of a "sustainable extractivism" for forest preservation and use. Maria do Espírito Santo da Silva was also a member of the socio-environmentalist group Conselho Nacional das Populações Extrativistas – CNS (National Council of Extractive Populations), and a leader of the Projeto Agroextrativista Praialta-Piranheira in Nova Ipixuna. She had a university studies.