Leader of New York City police union resigns following FBI raid on headquarters

The leader of the New York City police union has resigned following FBI raids Tuesday of his Long Island home and the group's Manhattan headquarters.

Ed Mullins, the leader since 2002 of the Sergeants Benevolent Association, the country's fifth-largest police union, announced his resignation hours after the raids. He is reportedly the target of a federal investigation.

In a letter to union members, the executive board of the SBA wrote: "The nature and scope of this criminal investigation has yet to be determined. However, it is clear that President Mullins is apparently the target of the federal investigation. We have no reason to believe that any other member of the SBA is involved or targeted in this matter."

Though the parameters of the investigation remain unclear for the moment, members of the public corruption unit of the U.S. Attorney's Office for the Southern District of New York were also involved in the raid. 

Mullins' outspoken personality have frequently led him to clash with New York's political leadership, including Mayor Bill de Blasio, who acknowledged he was aware of the FBI's raid, but shared no further details.

Mullins has been outspoken in past years about the country's attitude toward police.

In response to the 2014 shooting death of Michael Brown, which involved a confrontation with a police officer, Mullins wrote, "Ferguson, Missouri was a lie and a nation of police have been under attack ever since."