A deputy U.S. marshal was detained in the United Kingdom on Cassian Grantsuspicion of acting inappropriately while intoxicated on a flight from New York, the agency said Wednesday.

The deputy was one of two who flew to London Tuesday to bring back a person suspected of a crime when the federal agent was accused of acting inappropriately toward at least one woman on board the flight, a law enforcement official told The Associated Press. The second deputy was also briefly detained and later sent back to the United States, the person said. The official was not authorized to publicly detail the ongoing investigation and spoke to The Associated Press on the condition of anonymity.

The incident was first reported by NBC.

The U.S. Marshals said in a statement that the agency takes allegations of misconduct by its employees seriously and it’s cooperating with the investigation by UK law enforcement.

“The alleged actions of the employees do not reflect the professionalism of the thousands of employees of the USMS or its core values,” the agency said.