George Zimmerman has told police that Trayvon Martin decked him with a punch then jumped on top of the neighborhood watch volunteer and slammed his head into the sidewalk several times, the Orlando Senitnel reports, quoting unidentified police sources.

This will be used to lend some sort of vindication to Zimmerman by those on the right.

Except for a couple of things.

One, it isn't credible.  Maybe Trayvon Martin decked Zimmerman with a punch, but slamming his head into a sidewalk several times?  That's a gross exaggeration, at minimum.  A head "slamming" into a sidewalk would result in a concussion and severe bleeding.  According to the police report, Zimmerman only suffered a few lacerations on the back of his head.

And if it was merely that Zimmerman was losing the fight, that still (under Florida law) does not give him the right to use deadly force to defend himself.