Brazil has ousted almost all illegal gold miners from the Yanomami territory, its largest indigenous reservation, and will remove miners from six more reserves this year, the head of the federal police’s new environmental crimes division said on Tuesday.

Police are setting up new Amazon rainforest bases and are seeking international cooperation on law enforcement in the region, including the development of radio-isotope technology to prove the illegal origin of seized gold, Humberto Freire told Reuters.

Freire is the director of the newly-created environment and Amazon department of the federal police, marking what he called a new era in the battle against environmental crime and in defense of indigenous people in the rainforest.

Adding to the urgency in the early months of President Luiz Inacio Lula da Silva’s term, the government in January declared a humanitarian crisis in Yanomami territory.

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The territory had been invaded by thousands of gold miners threatening communities with firearms, driving deforestation, spreading malaria, polluting rivers and scaring off wild game, which led to malnutrition and hundreds of deaths.

“We still have some pockets of miners who are holding out by hiding in some areas, so we going through the Yanomami territory with a fine comb,” Freire said in an interview.

Enforcement operations supported by satellite imagery and aerial photography have destroyed 250 miner camps – many of which were already deserted – and 70 dredging rafts, along with speed boats and planes, he said. Police have seized some 4,500 liters of fuel and 1.2 kilos of gold, he added.

Police encountered and then released at least 805 miners and 94 boats on rivers, but most fled before the eviction operation.

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The police did not focus on arresting miners, Freire said, instead seizing or blocking 68 million reais ($13 million) of resources belonging to those accused of financing the illegal miners, while dismantling a prostitution network that took underage girls to the mining camps.

Junior Hekurari, head of the local indigenous health council, estimated that 85% of the gold miners had left or been forced out