Investigators so far have found firearms, explosives, spoiled food and a trench of human feces at the Malheur National Wildlife Refuge, federal prosecutors said.

The FBI is expected to take 21 days to complete processing "crime scenes'' at the federal property in Harney County, which includes 24 structures and an outdoor camping area, the prosecutors wrote in court records filed Tuesday.

The FBI Evidence Response Team began its work last Friday. The team initially found "significant amounts'' of human feces in and around the outdoor camping area and "large food stores that are spoiling'' in living quarters on the refuge outside Burns, Assistant U.S. Attorneys Ethan Knight and Geoffrey Barrow wrote.

Federal officials have found two large excavated trenches and an "improvised road on or adjacent to grounds containing sensitive artifacts,'' the prosecutors wrote.

"At least one of these trenches contains human feces,'' according to Knight and Barrow.

The prosecutors also noted that "the FBI is concerned that vehicles and buildings may be booby trapped."

They didn't specify what kind of explosives or guns had been been discovered or how many.

Ammon Bundy, 40, is now jailed on a federal conspiracy charge in Portland, accused of leading the Jan. 2 armed takeover of the wildlife sanctuary that lasted 41 days. The last four occupiers surrendered last week. Twenty five people have been named in indictments charging them with conspiring to impede federal officers from doing their jobs at the refuge.

Bundy has said he and his followers were demonstrating against the return to prison of local ranchers Dwight Hammond Jr. and his son, Steve Hammond, and the federal government's control of public land.

An FBI Art Crimes Team, known as ACT, is going over "a particularly sensitive cultural site'' next to or at the refuge's outdoor camping area, the prosecutors' memo said.

Their memo came in response to requests by defense attorneys for the government to preserve evidence in the case.

Prosecutors said they'll allow defense lawyers and their investigators to gain access to the refuge after the evidence has been collected but before the site is restored or open to the public.

Defense lawyers will be escorted by FBI personnel and won't be allowed to disturb or remove items from the scene, Knight and Barrow wrote.

The government further will make all evidence seized in the investigation available for inspection at the FBI field office in Portland, prosecutors said.

There appear to be some objections by defense lawyers to such an arrangement, which is expected to be worked out in court on Feb. 24.

Ammon Bundy's lawyers want access by an investigator and videographer to the refuge site immediately to observe the FBI's processing of the scene, according to court documents.

In a recorded message from jail, Ammon Bundy said he and other supporters who were at the refuge found rodents and animal droppings in buildings and tried to clean up the facilities.

Co-defendant Jason Patrick's attorney, Andrew Kohlmetz, had filed a request for the government to preserve any evidence and allow the defense access to the crime scenes. He also urged the court to manage the discovery of evidence in the case because of the number of defendants and size of the alleged crime scene.

-- Maxine Bernstein

mbernstein@oregonian.com

503-221-8212

@maxoregonian