WASHINGTON (CN) — Nearly 1,300 former Justice Department officials are calling for an internal investigation into Attorney General William Barr’s role in the violent clearing of peaceful protesters outside the White House last week.

Career and politically appointed officials who served under presidents from both parties, as far back as John F. Kennedy, urged Inspector General Michael Horowitz on Wednesday to immediately open a full investigation into possible law enforcement misconduct led by the attorney general.

“The rule of law, the maintenance of the department’s integrity, and the very safety of our citizens demand nothing less,” their letter states.

Law enforcement officers rapidly closed in on protesters gathered peacefully in Lafayette Square on June 1, firing tear gas, rubber bullets and flash bombs. But the demonstration continued in the week that followed, marked by cries for police reform in the wake of George Floyd’s killing while in police custody.

Barr has denied the sweep was intended to clear the area so President Donald Trump could walk over to the historic St. John’s Episcopal Church for a photo op holding a Bible. But the alumni of his agency called Barr out on Wednesday for participating in the politically motivated event by posing with the president for the photo.

The incident sparked a lawsuit from the Black Lives Matter movement, represented by the American Civil Liberties Union, arguing the administration had no legitimate basis to clear the park where political demonstrators regularly gather across the street from the White House.

The Justice Department alumni make the same argument as the ACLU that the officers in riot gear violated the protesters’ First Amendment right to free speech and Fourth Amendment right to freedom from unreasonable seizures, including unreasonable use of force.

“None of us would ever have considered directing or engaging in such actions to be consistent with our oaths to support and defend the Constitution,” the letter states.

The Justice Department released a statement in the last week that included a breakdown of the array of law enforcement officers deployed on June 1, among them units from the FBI, the Federal Bureau of Prisons and the U.S. Marshals Service.

But if the attorney general who was on site during the incident gave commands to the U.S. Park Police, D.C. National Guard and U.S. Military Police, it is unclear where he derived the authority to issue the orders, the agency alumni argue.

“Department of Justice and White House personnel initially said that the attorney general gave an order to law enforcement personnel to ‘get going’ or ‘get it done.’ A day later, the attorney general told the Associated Press that he was ‘not involved in giving tactical commands,’” the letter states, addressing the changing story from the agency as criticism mounted over the use of force.

David Thomas, professor of forensic psychology at Florida Gulf Coast University, said an investigation into Barr’s role in the clearing of protesters should look specifically at the events as they unfolded.

“That’s just like a police officer would be judged, those decisions that are made at that time. That’s how Chauvin, and those four officers in Minneapolis, that’s how they’re being judged,” Thomas said, referring to the officers charged in the killing of Floyd.

Thomas served for two decades as a police officer. Now an expert in use of force and policing, the professor said the law enforcement units on the street amid protesters violated the rules of engagement through use of force because the demonstration was peaceful.

The retired police officer said that if Barr is found to have violated the civil rights of peaceful protesters, he should be removed from office.

“That’s pretty powerful coming from a lowly cop, a retired cop, but that’s the standard,” he said. “If we’re going to hold police officers to that standard then we need to hold the attorney general to the same standard.”