(CNN) The Milwaukee Police Department said it has fired an officer for posting "racist" and "derogatory" content on social media about the arrest and tasing of NBA player Sterling Brown.

Brown was stopped in January in a drugstore parking lot over a parking violation. Erik Andrade, the fired officer, was one of eight officers on the scene, but he was not an arresting officer.

The incident prompted an internal affairs investigation, and Brown sued the city , Milwaukee's police chief and the officers for excessive force. Brown's lawsuit singles out Andrade for his social media posts, accusing him of mocking Brown with racist language and celebrating his arrest. CNN has reached out to Andrade and the Milwaukee Police Association, but they did not immediately respond to requests for comment.

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"Members are free to express themselves as private citizens on social media to the degree that their speech is not disruptive to the mission of the Department. However, speech, on or off duty, pursuant to members' official duties and professional responsibilities is not protected," Chief Alfonso Morales said in a statement.

Andrade's posts were in direct violation of that policy, Morales said.

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