this is not the medical examiner who performed the autopsy on trayvon martin. instead, it is a witness who was called on by the state to examine this question given the wounds we've seen on zimmerman's head, was he really in danger of being killed himself? images of george zimmerman bloodied and beaten up, important visuals for his defense, trying to show that zimmerman's head had been slammed against the sidewalk and we to fire his gun to save his own life. that's not the way jacksonville based medical examiner valerie rao sees it. >> are the injuries consistent with having been repeatedly slammed into a concrete service. >> reporter: no. >> reporter: rao testified the injuries were not life-threatening, consistent with being punched or hitting a concrete surface once but during cross-examination, rao admitted when pressed by attorney mark o'mara he could have been hit multiple tiles. the jury also heard from a man