The killers came from the forest, the very same forest Raimundo Santos Rodrigues so loved.

The environmentalist had spent years defending one of the last pristine swathes of the eastern Amazon rain forest from loggers, miners and farmers. But his activism had earned him enemies in Brazil’s northern state of Maranhão.

And on Tuesday afternoon, those enemies pounced.

Santos Rodrigues and his wife were riding their motorbike from the market back to the Biological Reserve of Gurupi when two men suddenly emerged from the treeline, witnesses told local media. As the couple crossed a bridge, the gunmen opened fire, hitting both the environmentalist and his wife.

To ensure their objective, the assassins ran up to Santos Rodrigues and stabbed the injured man to death. His wife, Maria da Conceição Chaves Lima, was rushed to the hospital and is expected to live.

Santos Rodrigues had been a “marked” man because of his environmentalism, said a man who spoke to G1 anonymously for fear of also being targeted.

“Loggers hated him because he denounced them,” said a co-worker, also anonymously. “He was very active in the region, defending the community, attending the Union of Rural Workers of Bom Jardim.”

Officials have promised a thorough investigation and are treating the murder as an attack on a public official. Santos Rodrigues was a volunteer with the Chico Mendes Institute for Biodiversity Conservation, part of the Ministry of the Environment.

“It will be treated with top priority,” said Alexandre Saraiva, a federal police superintendent.

But that promise appears hollow against the bloody reality in Brazil, widely considered the most dangerous country on earth for environmentalists.

Between 2002 and 2013, at least 448 environmentalists were killed in Brazil, according to Global Witness. That equates to roughly half of all the environmentalists murdered worldwide during that period.

According to local watchdog CPT, the grim tally is even worse: More than 1,500 Brazilians have been killed over the past 25 years fighting deforestation, and another 2,000 have received death threats, Men’s Journal reported in 2012.

Last year, 29 Brazilian environmentalists were murdered, again more than any other country, according to Global Witness.

The reasons behind Brazil bewildering conservationist killing spree are simple. The country’s land ownership is “among the most concentrated and unequal in the world,” leading to conflicts between subsistence farmers or indigenous groups and “well-connected landowners over who has the legal right to forests and land,” according to Global Witness.

“Magnates buy off local politicians and policemen, and kill anyone who challenges their agricultural practices,” according to Men’s Journal.

As in the slaying of Santos Rodrigues, environmentalists are in most danger inside or at the edges of the Amazon. The giant rain forest — which some activists fear will be half gone by 2030 — is the site of 68 percent of all such murders, according to Global Witness. First the trees are cut down by loggers, which then opens the land up to cattle ranchers, soy farmers or miners.

“Many people from the logging and mining companies think the only way to solve problems is by killing the people who defend the forest,” federal prosecutor Felício Pontes told Men’s Journal.

Like the Amazon itself, the problem of violence against environmentalists is shared by many Latin American countries. Last year, at least 25 environmentalists were killed in Colombia, according to Global Witness. Honduras (12), Peru (9), Guatemala (5), Paraguay (3) and Mexico (3) also reported multiple murders of conservationists in 2014.

Although more than 80% of the killings were in Latin and Central America, Asian environmentalists are also at great risk. Fifteen Filipinos were killed in 2014, followed by Thailand (4), Indonesia (2) and Myanmar (2), again according to Global Witness.

Almost none of these murders are ever solved, the group says. A 2014 Global Witness report found that 908 activists were killed in 35 countries between 2002 and 2013, yet there were only 10 convictions.

“What feeds the violence is the impunity,” Isolete Wichinieski, national coordinator of the Brazilian group Commisão Pastoral da Terra, told the Guardian.

The problem is particularly vexing in Brazil, a country with a strong activist community — one partly created by past incidents of violence.

The conservation agency for which Santos Rodrigues was working at the time of his murder is named after Chico Mendes, Brazil’s most famous fallen environmentalist. A rubber tapper, union activist and defender of the Amazon, Mendes was murdered on Dec. 22, 1988. He had received death threats because of his efforts to protect the rain forest from cattle ranchers. But policemen assigned to protect him were instead playing dominoes when a rancher crept up to Mendes’s house and shot him as he showered, according to the Guardian.

“It was like shooting a jaguar,” the rancher, Darcy Alves, said. He and his father, Darly, were convicted and sentenced to 19 years in prison.

Mendes’s murder led to the establishment of huge environmental reserves, or rebios. But it didn’t stem the violence against his fellow activists.

On Feb. 12, 2005, two assassins shot 73-year-old Sister Dorothy Stang to death as she read aloud from her Bible. The Ohio-born nun had earned the ire of landowners intent on cutting down the Amazon.

“On the 10th anniversary of Stang’s slaying, the nuns still advocate on behalf of the small-scale farmers, and the scourge of land conflicts in the Amazon has not been resolved,” the AP reported earlier this year.

Perhaps the most disturbing environmentalist murder occurred in May 2011. Eerily, it was a near carbon copy of Tuesday’s killing.

José Claudio Ribeiro da Silva, known as “Ze Claudio,” was a rubber tapper and activist like Mendes. When Ribeiro da Silva organized protests against the illegal logging of public land, he and his wife received a death threat: “Get ready to be silenced forever.”

In November of 2010, Ribeiro da Silva made a defiant speech in Manaus. “I live from the forest, I’ll protect it at any cost. And that’s why I live with the constant threat of a bullet to my head, because I denounce the loggers and charcoal producers,” he said. “I’m here talking to you today, but a month from now I might have disappeared.”

Six months later, Ribeiro da Silva narrowly survived an assassination attempt when shots were fired into his backyard. Finally, on May 24, 2011, his luck ran out.

Like Santos Rodrigues four years later, Ribeiro da Silva and his wife were riding home on their motorcycle when they were ambushed. Masked men sprang out from nut trees and shot the couple 15 times, then cut off Ze Claudio’s ear as proof of their kill, Men’s Journal reported.

Although two men were convicted for the killing, the farm-owner who accused of paying for the killings escaped punishment.

On the same day Ribeiro da Silva and his wife were killed, the Brazilian congress voted to amend the country’s forest code to grant ranchers amnesty for illegal deforestation. The change also reduced the percentage of land that ranchers are required to preserve.

“Brazil woke up to the news of the murders of two leading environmental activists, and it’s going to bed with the murder of the forest code,” Greenpeace Brazil ecologist Paulo Adario said at the time.

The outcry over Ze Claudio’s killing spurred the government to announce it would provide activists with protection, but few have actually received it, Pontes told Men’s Journal. And although violence against Brazilian environmentalists has ebbed slightly since its peak in 2011, when 106 were killed, the underlying problems are only getting worse.

“The enforcers of Brazil’s environmental law are not winning the war,” the Chicago Tribune reported in July. “Government data show that after years of improvement, deforestation rates stopped decreasing in 2012. The country entered recession last year, and farming is one of the few sectors that keep the economy going.”

“People here have stopped believing in the law, if they ever did,” Manoel Malinski, a local official told the Tribune.

As Brazil’s economy stutters to a halt, resources for fighting deforestation will only dry up. And the temptation to cut down precious rain forest will only increase. That could lead to more conflict, and more killings.

“We may be seeing just the tip of a much larger iceberg,” Bill Kovarik, a Radford University professor who tracks violence against environmentalists, told Smithsonian magazine last year. “The world needs to be aware of the people who are dying to save what’s left of the natural environment.”