You would put your Celebrity career at risk(endoresment, contracts, etc etc.), against the advisement of your publicist & agent, to publicly back a friend that was accused of felony level stuff?
I think private support and public silence is more than enough on the matter. Maybe a character statement*, but I wouldn't risk it all to show 100% friend loyalty just for the media's sake, and I don't think your friend in trouble would want that either.
*"I've known so & so for so long, and I would never believe that so & so is capable of such a thing. If this news were true it would be as big of a surprise to me as it is to you, but I don't believe it for one second"