In a memo dated April 17 that was also released Monday, the department instructed its security officers to review its policy for the use of force, emphasizing the directive that “the safety of innocent persons and officers is of paramount importance.” All four officers involved in Dr. Dao’s removal have been placed on administrative leave.

The release included personnel files for all of the officers involved, including Officer Long, Officer Steven L. Smith, Officer Mauricio Rodriguez Jr. and Sgt. John Moore, as well as the notice given that each was being put on administrative leave. Officer Long and Sgt. Moore had each been disciplined for minor, non-violent incidents in the past.

The department also released audio of the original call in which the airline asked for help.

“Two passengers are refusing to get off the aircraft when instructed by the agent and also the supervisor,” an airline employee tells the police dispatcher. He could not give a description of the passengers.

“Any information on were they drinking, were they doing anything like that?” the dispatcher asks a little later in the recording.

“No, it’s something with an oversold and didn’t volunteer or something like that,” the United employee responds.

In fact, the flight was not oversold. United was attempting to make seats available for a flight crew that needed to be in Kentucky for flights the next morning. The airline tried to get volunteers, but when no one stepped forward four people were selected and told to leave. Two complied, but Dr. Dao refused, saying he had patients to see the next day.

Multiple passengers made videos of the physical confrontation that followed, in which Dr. Dao was dragged down the aisle by his arms. He was later seen returning to the flight with a bloodied mouth in a state of confusion. He was eventually removed in a stretcher.