CHICAGO (AP) — Federal prosecutors have reached a last minute plea bargain with a black man after his attorneys discovered alleged white supremacist social media posts involving a potential key witness, who is a veteran Chicago police officer.

The Chicago Tribune reports that Sean Najm is among the officers who arrested 25-year-old Edwin Brown for drug and weapons charges. Najm denies that any of the Facebook posts are racist and insists he has innocent explanations for them.

Facebook posts show Najm also belongs to a motorcycle group called the American Knights, which describes itself as a club that promotes “motorcycle riding with like-minded people.”

Brown pleaded guilty Thursday to possessing heroin with intent to deliver in return for a dropped gun charge. He has been released and permitted to stay with his grandmother.