Chances of getting away with it?

After a local club that we visited closed last night, a local cop was helping with the security detail(clearing patrons out of the parking lot). A friend of mine snuck up on the police officer while he was arguing with another person and cold-****** him in the face..knocking the officer out.(My friend is a big dude). Neither my friend nor I knew anyone attending the club last night...and the officer never got a chance to look at my friend before getting KO'd. I know for a fact that the club doesn't have outside cameras that would have filmed the situation(I asked a bouncer about it after my friend left). Is it possible my friend might get away with aulting an officer?