The U.S. Department of Justice's Office of Inspector General is investigating several elite FBI agents who responded to the 2016 occupation of the Malheur National Wildlife Refuge.

A filing in federal court Wednesday characterized it as a "lack of candor investigation."

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One of the agents under investigation is W. Joseph Astarita, a member of the FBI's Hostage Rescue Team. Astarita stood trial in August on charges of lying to investigators and obstructing justice following the shooting of occupation spokesman Robert "LaVoy" Finicum. A jury acquitted Astarita of those charges.

The government court filing doesn't name other agents under investigation or say how many may be. The Office of Inspector General declined to comment.

Related: FBI Agent Accused Of Lying In Finicum Shooting Found Not Guilty

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"Lack of candor is one of the most serious things you can be accused of or charged with in the FBI," said Greg Bretzing, the former special agent in charge of the FBI’s Portland Division, who oversaw the response to the occupation. "If you lie or withhold evidence, you're likely going to lose your job if you're an FBI agent."

In this case, the lack of candor investigation is administrative. The Office of Inspector General would likely turn any findings over to the FBI, which would then take any punitive actions the agency deems necessary.

In a report released in April, the inspector general found four instances where former FBI Deputy Director Andrew McCabe lacked candor when questioned about his conversations with a reporter at The Wall Street Journal. McCabe was fired in March.

David Gomez, a former FBI agent and fellow at the George Washington University Center for Cyber and Homeland Security, said the investigations are subjective.

"That truth is subject to the interpretation of the interview," he said. "It's not any different than what prosecutors will do in terms of charging a defendant."

Gomez said these types of investigations can be a way to coerce or force people to admit things they didn't necessarily see as violations of the rules.

"It's common enough that I think it's problematic," he said. "An investigation for a violation of rules and procedures in the FBI can get you suspended for one to 60 days, but lack of candor during the investigation will get you fired."

Astarita's attorney didn't return calls.