The FBI on Tuesday raided the offices of a New York City police union in Manhattan.
In addition to executing a search warrant at the headquarters of the Sergeants Benevolent Association, an FBI spokesperson said the bureau was also searching a home in the Long Island suburb of Port Washington.
That home belongs to the SBA's outspoken leader, Ed Mullins, sources told NBC News.
It was not immediately clear why the FBI targeted the SBA, which represents 13,000 members of the New York City Police Department and is the fifth-biggest police union in the country.
New York City Mayor Bill de Blasio said he was aware of the FBI raid but provided no details.
Mullins, who has run the union since 2002, could not immediately be reached for comment. But he has frequently clashed with both the NYPD leadership and De Blasio.
The union leader's acerbic twitter posts have included calling a city councilman a “first class whore”, calling a former health commissioner a “b----”, and in response to the officer involved shooting death of Michael Brown and subsequent protests he said, “Ferguson Missouri was a lie and a nation of police have been under attack ever since.”

New York City police union leader resigns after FBI raid on headquarters
Leaders of the Sergeants Benevolent Association, which represents 13,000 members of the NYPD, revealed Ed Mullins' resignation in a letter to members.