An eyewitness to Trayvon Martin's killing appeared on Anderson Cooper's AC360 on CNN last night and said that George Zimmerman appeared to walk away from the scuffle uninjured but, "very worried," casting more doubt on Zimmerman's self-defense claim. For the past week, Zimmerman's friends and family have vouched for his character while his father and his defense attorney have continuously brought up Zimmerman's alleged injuries at the hands of Martin. Earlier this week, police video of a seemingly unharmed Zimmerman drew attention. And now, there's an eyewitness account to go along with those images. The witness, whose name and identity were withheld, told Anderson Cooper last night:

I don't know if was an echo but it definitely made more than one pop ... After the larger man got off there was a boy, obviously now dead, on the ground facing down...

It was dark. I can't say I watched him get up, but in a couple of seconds or so he was walking towards where I was watching and I could see him a little bit clearer. It was a Hispanic man. He didn't appear hurt or anything else. He just kind of seemed very worried with his hand up to his forehead.

The witness also added that he saw no blood and that the confrontation took place on grass, contradicting the claim that Zimmerman was wounded in the back of the head because Martin was slamming his head into the pavement.  Here's video of the interview (CNN):