Details about the police response to the armed takeover of the Malheur National Wildlife Refuge - from how many FBI agents were involved to the types of firearms they carried - aren't relevant to the conspiracy case against the refuge occupiers, federal prosecutors argued in court papers.

They also want to file a memo under seal and only with the judge about the U.S. Department of Justice's investigation into shots apparently fired by an FBI agent at Robert "LaVoy'' Finicum and alleged tampering with evidence afterward at the scene.

Assistant U.S. Attorney Charles F. Gorder Jr. described that investigation as "ongoing,'' in a legal brief filed in court Wednesday.

Defense lawyers in the Oregon standoff case oppose sealing the memo. They've asked the judge to compel the government to turn over the investigative records into the FBI's alleged misconduct.

Defense lawyers have argued that prosecutors must share any evidence that could benefit the defense, including any material that could damage the credibility of a prosecution witness. They say the evidence is important to help show that those who seized the refuge were armed "in fear of a covert FBI attack'' and to establish the "bias and animosity'' of the elite FBI Hostage Rescue Team involved in shooting at Finicum.

Federal prosecutors counter that they won't call law enforcement officers involved in the investigation as witnesses at trial, according to court records.

By late Wednesday, U.S. District Judge Anna J. Brown said she'd allow prosecutors to file the memo under seal, but it must be shared with defense lawyers.

Defense lawyers also have asked the court to force the government to provide other general information about the law enforcement response to the 41-day takeover that began Jan. 2.

Among the material they're seeking: rules of engagement for each law enforcement agency that responded; any records planning for arrests; the number and identities of every law enforcement officer present on each day of the occupation; the number of officers who wore body armor or tactical gear each day; the number and types of aircraft and vehicles law enforcement used; any information regarding the fortification of the Harney County courthouse; and records of daily law enforcement briefings.

Assistant U.S. Attorney Geoffrey Barrow argued that the information is irrelevant to the conspiracy and weapons case against defendants. A jury won't be asked to decide if the FBI or state or local police responded appropriately to the occupation, he said.

"Whether law enforcement responded to the armed takeover with 100 officers or 500 officers, and whether half or all of those officers wore body armor has no bearing on this case,'' Barrow wrote in the government's response. "Defendants arrived at the refuge office armed; there is no suggestion that they secured firearms only after law enforcement responded to the scene.''

It's unlikely that documents detailing a daily inventory of officers and their equipment exist, he said. Instead, the information would have to be compiled from multiple sources and would be "extraordinarily burdensome,'' he said.

A federal grand jury indicted Ammon Bundy, the occupation's leader, and 25 co-defendants on a federal charge of conspiring to impede federal workers at the federal wildlife sanctuary outside of Burns. Four have pleaded guilty to the conspiracy charge and one more is expected to do so Thursday.

A trial for many of the remaining defendants is set for Sept. 7. Bundy has said the occupation was held to protest the return to federal prison of two Harney County ranchers and federal control of public land.

Bundy and other key figures were arrested as they were driving from the refuge to a community meeting in John Day on Jan. 26.

Finicum, the occupation spokesman, swerved his truck into a snowbank to avoid an FBI and state police roadblock on U.S. 395. As Finicum emerged from the truck, an FBI agent with the Hostage Rescue Team fired two shots, but none of the team members admitted to discharging their firearms, the Deschutes County sheriff alleges.

Oregon investigators concluded one shot hit the roof of Finicum's truck and the other shot missed. A state trooper later described to investigators seeing two rifle casings in the area where the agents were posted. Detectives investigating didn't find the casings, police reports indicated. Moments later, state police fatally shot Finicum as they said he reached into his jacket for a loaded handgun.

-- Maxine Bernstein

mbernstein@oregonian.com

503-221-8212

@maxoregonian