Stang, a naturalized Brazilian born in Dayton, Ohio, spent 30 years protecting the rainforest and made enemies among loggers and ranchers who coveted its lucrative resources.

She was shot in a dispute with a local rancher who was encroaching on a peasant settlement she helped set up near the town of Anapu, 930 miles (1,500 km) north of the capital, Brasilia.

Police have charged five men in connection with her death, including a rancher who allegedly ordered her murder.

Lawmakers and human rights activists suspect the five were part of a wider plot by powerful land holders and have joined Stang's brother to demand the government dig deeper.

"Mr. Bastos said he really does want to continue the investigation into this crime," said Stang, 77, wearing a T-shirt with his sister's smiling face, after he met Justice Minister Marcio Thomaz Bastos.

Brazilian President Luiz Inacio Lula da Silva sent 4,000 troops and hundreds of police into Para to end lawlessness in the region after Stang's murder drew global attention.

Nearly eight months later, critics say promises to speed establishment of federal landless peasant settlements and protect peasants and land activists are largely unmet.

Peasant farmers still face death threats in the Anapu region where there have been three killings since February, human rights lawyer Jose Batista Afonso said.

Illegal loggers and ranchers still hire gunmen with impunity to force peasants out of areas, he said.

"There are several powerful people behind the crime of Sister Dorothy and others who are walking around in freedom," said Afonso of the Para wing of the Pastoral Land Commission, a human rights group linked to Brazil's Catholic Church.

Agrarian Reform Minister Miguel Rossetto told Stang the five defendants would face trial by the end of the year and backed up Bastos' promise for an ongoing federal probe.

He promised action in 10 days to speed up creation of sustainable farming hamlets.