Ummm... a HOST of possibilities. I'm going to let you in on a little secret... people lie and groups of people together typically do this for sensationalism. This is especially true for people interacting with police officers. It's not uncommon for an officer to be sued or taken to court over a BS story of some sort of abuse. They teach at the academy that you might as well prepare for it, b/c if you're doing your job, someone will try to trash you. If it comes out and they did it, they'll be charged. Until then, this thread is a waste.
Ummm...fill us in on some of these possibilities. And it's no secret that police lie and police in groups have lied that's not up for debate. And what do you mean if it comes out they did it? You mean accidentally or purposefully? Do you think someone else beat him and the cops just came onto the scene? This sounds like a case of cops with batons gone wild. Its okay, it happened in CA and you are in IN it doesn't reflect badly on you so you don't have to defend it. We know there are BS stories out there, an MSP buddy of mine has his own youtube video about choking an "innocent man" according to the title, turns out he wasn't so innocent in the end though. I've known that guy for over 13 years and was a DS on active duty with him and he's one of the most above board guys you'll meet, he's big but quiet and respectful, so I know it does happen.
http://www.youtube.com/watch?v=7keDYxOAMn4