A police officer has been taken off patrol duty after turning over a driver who was involved in a traffic accident to immigration authorities, an official said.

Chief Edwin Roessler of the Fairfax County Police Department in Northern Virginia said that he had ordered an investigation into the episode, which occurred last month.

He also reiterated policy that officers have no authority to enforce federal law. He did not identify the officer, who was “relieved of all enforcement duties,” or the driver.

“As a matter of full transparency to our community — our police officer violated our long-standing policy and deprived a person of their freedom, which is unacceptable,” Mr Roessler said.

“Our county is one of the most diverse counties in the nation and no one should have the perception that FCPD is acting as a civil immigration agent for ICE,” the chief said, referring to Immigration and Customs Enforcement. “This matter damages our reputation and the long-standing policy that I have stated many times, that our officers shall not act as immigration agents.”

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The episode took place on the afternoon of 21 September when a Fairfax County police officer was handling a traffic accident in the Groveton community, south of the city of Alexandria, the chief’s statement said.

The officer found that one of the drivers involved in the accident did not have a Virginia driver’s license, and conducted a check to verify the person’s Department of Motor Vehicles record, the statement said.

In doing so, the officer received a notification from ICE that the driver was wanted on an administrative violation warrant for failing to appear for a deportation hearing.

The officer then contacted the ICE agent listed on the warrant, gave the driver a summons for not having a license, and after the person signed the summons, the officer detained the person, the police statement said. The officer then turned over custody of the driver to the ICE agent at the location of the accident.

Mr Roessler said the department’s arrest policy since 2007 and its training had been “very clear” that personnel do not enforce administrative warrants or take people into custody for them. He said that the driver was released from ICE custody after three hours and issued an ankle monitor.

The chief did not provide the length of the officer’s service. He said in an interview on Wednesday that he learned of the interaction through an email to his account, and that after the investigation, it was likely the officer would be back on patrol duties by Friday.

He said that the officers in the department do not have the right to enforce civil matters, which can range from administrative warrants to evictions.

“Once the person signs the summons, they are free to leave,” the chief said. “The engagement should have been over.”

Mr Roessler said that the officer’s administrative leave with pay required remedial training.

Asked about the case, ICE said in an email that its partnerships with law enforcement agencies were “essential to maintaining public safety.” But it deferred comment on the Fairfax County case to the police department there.

The episode was another example of how the lines between the duties of local law enforcement departments have become blurred with those involved in ICE’s federal enforcement activity, even in cases where there is policy laying out the boundaries.

Some states have laws that limit how much the local police can cooperate with immigration authorities, forming so-called sanctuary cities. In 2017, president Donald Trump signed an executive order saying he would halt funding to municipalities that did not cooperate.

Naureen Shah, a senior advocacy and policy counsel for the ACLU, said she had heard stories similar to the one in Fairfax County of local law enforcement turning people over to ICE, even when there are policies that limit such cooperation.

“All over the country there are hundreds of cities that have policies like that, that say, ‘We are not going to act as rogue agents or vigilante immigration officers,’” she said.