Defense lawyers in the Oregon standoff case want a federal judge to compel the government to turn over records from its investigation into the apparent firing of gunshots by a FBI Hostage Rescue Team member at Robert "LaVoy'' Finicum and alleged tampering with shell casings after the Jan. 26 encounter.

They're asking for all the reports developed by the Inspector General's Office of the U.S. Department of Justice and Oregon's Tri-County Major Incident Team led by the Deschutes County sheriff.

"The Office of Inspector General (OIG) is investigating members of the FBI Hostage Rescue Team (HRT) for lying to crime-scene investigators about their involvement in the shooting incident and for tampering with evidence,'' Attorney Per C. Olson wrote in a memo supporting his motion.

Olson, the court-appointed lawyer for defendant David Fry, and Attorney Terri Wood, court-appointed lawyer for Jon Ritzheimer, filed their motions in U.S. District Court on Tuesday afternoon.

Prosecutors must share any evidence that could benefit the defense, including any material that could damage the credibility of a prosecution witness.

Federal prosecutors said they won't call law enforcement officers involved in the investigation as witnesses in the case, according to court records.

The government also doesn't believe they must give the defense any additional information regarding the investigation in the pending conspiracy and weapons case stemming from the occupation of the Malheur National Wildlife Refuge in Harney County, the records show.

The defense lawyers countered that the evidence is important to help show that those who seized the refuge were armed for "defensive purposes'' and "in fear of a covert FBI attack'' -- and not to interfere with federal workers at the refuge. They also need the investigative reports to establish the "bias and animosity'' of the elite FBI Hostage Rescue Team officers "directly involved in the shooting and subsequent cover-up,'' Olson said.

U.S. District Judge Anna J. Brown said Wednesday in court that the matter is an "important issue'' to address, and she asked prosecutors to file a response to the defense motions by June 24.

Twenty-six people were indicted on federal conspiracy and other charges in the 41-day refuge takeover that began Jan. 2. Three have pleaded guilty to the conspiracy charge and two more are expected to do so this week. A trial for many of the remaining defendants is set for Sept. 7, though some of the accused have waived their right to a speedy trial. Leader Ammon 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 evaded the police stop on U.S. 395, and swerved his truck into a snowbank to avoid an FBI and state police roadblock. As Finicum emerged from his truck, two shots were fired from an FBI agent with the Hostage Rescue Team, though none of the team members admitted to discharging their firearms, the Deschutes County sheriff alleges.

Five FBI agents assigned to the traffic stop told investigators that none of them fired at Finicum's pickup after it crashed. Oregon investigators, however, concluded that one agent fired twice at the truck, hitting it in the roof and missing on the second shot. 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.

State troopers later shot and killed Finicum moments later as he reached inside his jacket. He had a loaded handgun in a pocket, investigators said.

Olson said he's also seeking the investigative reports to show that Fry, the last holdout from the refuge occupation who surrendered on Feb. 11, continued to have guns because he feared "a similar violent and covert attack by the FBI,'' Olson wrote.

The Inspector General's investigation also is relevant, the defense lawyers argued, because it's an extension of the arrest reports involving defendants Shawna Cox and Ryan Bundy, who were rear-seat passengers in Finicum's truck.

"These defendants are entitled to know why an FBI agent shot at them and then covered it up,'' Olson wrote in his legal filing.

Ryan Bundy suffered a wound to the right shoulder, Olson wrote.

According to Olson's filing, the Deschutes County sheriff concluded that: "The FBI HRT team members lied to investigators on January 26, 2016, by denying they had discharged their weapon; The FBI HRT team members lied to investigators on February 5 and 6, when they again denied having discharged their weapons; and the HRT members' attempted to cover up the shots by 'picking up their brass following the shooting.' "

While the Deschutes County sheriff and district attorney found state troopers were justified in their fatal shooting of Finicum, the question remains whether the two earlier gunshots from an FBI agent with the Hostage Rescue Team were justified, Olson wrote.

Oregon's FBI special agent in charge, Greg Bretzing, cautioned at a news conference in March that it hadn't yet been resolved who fired the two mystery shots. The Justice Department's Office of Inspector General has made no reports from its investigation public.

Evidence already shared with defense lawyers doesn't include the interview reports or transcripts of the FBI HRT operators' statements to the investigators or their names or field offices, Olson noted.

"One trooper described the FBI HRT members as mysterious and expressed doubt whether they used their true names even with other law enforcement,'' Olson said.

"While a man lay dead in the snow, federal agents with a greater concern for their reputations than the grave matter at hand conspired to hide evidence of their discharge of weapons,'' Olson wrote. "The FBI's pattern of conduct demonstrates an attitude of being above the law and not accountable to anyone. This attitude is relevant to assessing the credibility of the agents' testimony.''

Despite federal prosecutors' contention that they won't call the FBI agents who are under investigation as witnesses, Olson argued, "At the very least, the defense needs to know whether any testifying FBI agent had any involvement whatsoever with the Finicum shooting or the aftermath.''

The defense lawyers argue that the evidence is important to show a pattern of FBI excessive force, citing the FBI's aggressive and deadly showdowns at Waco, Texas, and Ruby Ridge, Idaho, in the early 1990s. Olson also noted that in this pending case, the FBI questioned Fry at length after his arrest, despite notice from his defense lawyer that Fry wasn't to be interrogated.

-- Maxine Bernstein

mbernstein@oregonian.com

503-221-8212

@maxoregonian