The juror was replaced Friday by the lone alternate, which means deliberations will have to start over.
On Thursday, after two days of deliberations, the jury sent out a note saying the now-released juror claimed the defendant, Richard Kern, had been previously convicted of police brutality.
There had been two civilian complaints made against Kern, but he was exonerated both times.
The other jurors said they were not affected by the claim.
Michael Mineo claims he was sodomized him with a police baton at a subway station in Brooklyn.
Kern has pleaded not guilty to aggravated sexual abuse and assault. Two other officers have pleaded not guilty to hindering prosecution.