(CNN) — The occupiers left, but evidence of them remains at Malheur National Wildlife Refuge in Oregon.
Investigators processing the site have found human feces, spoiling food, firearms and explosives, according to documents filed this week by federal prosecutors in response to a defense request to access the location.
The news drew swift condemnation from members of the Burns Paiute tribe, which considers the refuge sacred ground.
“Of course I have anger,” said tribal council member Jarvis Kennedy. “It would be like someone going out to Arlington National Cemetery and doing the same thing. That’s how we see it.”
The documents state that teams responsible for securing the refuge reported “significant amounts of human feces in and around an outdoor camping area,” which “is adjacent to or on a particularly sensitive cultural site that may require extensive processing.”
“Occupiers appear to have excavated two large trenches and an improvised road on or adjacent to grounds containing sensitive artifacts. At least one of these trenches contains human feces,” the documents read.
“Finally, firearms and explosive have been found on the site. There are numerous vehicles on the site and the FBI is concerned that vehicles and buildings may be booby trapped.”
The 41-day occupation of the federal wildlife refuge ended last week when the four remaining protesters surrendered to authorities.
Last month, one of the leading occupiers was killed by authorities in a highway incident, during which protest leader Ammon Bundy and others were arrested.
On Wednesday, Bundy released a statement through his attorneys, saying he did his best to preserve the artifacts at the refuge when the standoff began.
Bundy said his group reached out to members of the the Burns Paiute tribe “multiple times” to offer to take them the artifacts they had gathered because “we understood they were something that was sacred and they were not ours.”
Bundy and other protesters started out demonstrating against the sentencing of Dwight Hammond and his son Steven, ranchers who were convicted of arson on federal lands in Oregon.
But a January 2 march supporting the Hammonds led to the armed occupation of the refuge building, with protesters decrying what they call government overreach when it comes to federal lands.
CNN’s Seth Kovar and Amanda Watts contributed to this report.