Early last Tuesday, José Cláudio Ribeiro da Silva, a forest activist and tree nut harvester, and his wife, Maria do Espirito Santo, drove a motorcycle through Brazil’s northern Para State, in the Amazon rain forest. As they crossed a river bridge, gunmen lying in wait opened fire with a pistol and shotgun, killing them.

It was a gruesome attack: before they fled, the assassins severed one of Mr. da Silva’s ears as a trophy, a signature of hired gunmen in the region. At least 15 bullet casings were found at the scene, reports said.

News of the slayings, emerging on the same day that Brazil’s parliament was to vote on a controversial revision of the country’s forest protection laws, rocketed through Brazil’s political classes. Within hours, senior government officials were briefed on the crime and President Dilma Rousseff had ordered an investigation by the federal police.

Yet whether that investigation results in punishment for the killers — or those who likely hired them — is deeply uncertain. More than 1,000 rural activists, small farmers, religious workers and others fighting the region’s rampant deforestation have been slain in the past 20 years, but only a handful of killers have ever been successfully prosecuted, according to a statement by the Pastoral Land Commission, a Catholic organization that tracks rural violence.



The successful prosecution of the powerful farmers, ranchers, loggers and industrial interests behind the killings, meanwhile, is almost nonexistent in the region, the group said.

Environmental campaigners said that endemic corruption in Para State’s judiciary has allowed the murder of forest activists to be committed with impunity.

“Corruption is part of the process here,” said Paulo Adario, the Amazon campaign director for Greenpeace. “Para is a state completely out of control. It continues to be the Wild West.”

In a speech at the TEDx Amazon conference last November, Mr. da Silva spoke about his efforts protecting the rain forest, where he had worked as a nut harvester and basket maker since the age of 7 and had helped develop an economic collective based on sustainable forest products. (For English subtitles on the above YouTube video, press play, then engage the “cc” closed-captioning button.)

As a child, he said, the forest cover around his small town was 85 percent intact, but today it is down to just 20 percent, much of which is already fragmented.

He acknowledged the dangers he faced for his activism. “I live off the forest, I protect it in every way I can. That’s why I live at gunpoint all the time,” he said. “Am I scared? I am. I am a human being. I get scared.”

Mr. da Silva closed his speech with a plea to “all of you who live in urban centers.”

“When you want to buy something that was made from timber, that came from the forest, check the origin,” he said. “If you start to say no to timber of suspicious origin, to timber with an unknown origin the market will begin to weaken and they will no longer see the results they hoped for.”

“They either abide by the law or they close down.”

In a grim coincidence, on the same day that Mr. da Silva and his wife were killed, the Brazilian Congress voted in favor of a controversial bill loosening the national forest code, a decades-old law containing provisions designed to protect the Amazon rain forest from destruction by loggers, farmers and other commercial interests.

The law would open the door to new deforestation and grant broad amnesty to those guilty of illegal forest clearance, analysts said.

During the debate over the revisions, Jose Sarney Filho, a congressman and former environment minister who opposed the changes to the code, spoke of the activists’ murders in a speech to the Assembly. He was greeted by boos from the audience, including fellow deputies.

“I couldn’t believe it,” said Mr. Adario, the Greenpeace director, who witnessed the speech. “They were booing the news of a murder. It was terrible, but it happened.”

The bill now advances to the Senate for review, and must ultimately be signed by President Rousseff, who has vowed to veto any measure containing amnesty for illegal loggers or allowing new deforestation.

As for the investigation into the murders of Mr. da Silva and his wife, regional observers say that justice is unlikely unless sufficient media and political pressure are brought to bear on the case.

A similar slaying in 2005, of Dorothy Stang, an American nun and rain forest activist, resulted in the conviction not just of the gunmen responsible for her death but also the powerful landowner who ordered the killing. Those convictions came only after intense national and international attention and a difficult legal process, however.

“This is a very remote region, far from the spotlight,” Mr. Adario said. “When you bring the spotlight you can hope that things can change.”