WFTV in Orlando reports that the autopsy report on Travyon Martin showed broken skin on his knuckles, suggesting that he was involved in a fight before being shot and killed by George Zimmerman. According to the TV station, that and the single gun shot wound were the only injuries on his body. In addition, ABC News has received a different medical report on Zimmerman that says he had a broken nose, two black eyes, and a cuts on the back of his head the day after the shooting. That report came from a family practice physician that Zimmerman sought treatment from the morning after the incident.
Combined together the new medical evidence does seem to confirm the story that Martin and Zimmerman were involved in some kind of altercation before Martin was shot, but there's still no way to know how it may have started. Zimmerman claims he was jumped by Martin, but prosecutors will likely argue that Zimmerman was the instigator, as he was following Martin through the neighborhood at night. Zimmerman was charged with second-degree murder and is out on bail. The next court hearing will be later this month.
The doctor's report on Zimmerman also says he complained of "occasional nausea when thinking about the violence," but that he did not have a concussion. Finally, it says that Zimmerman had previously been prescribed the medications Adderall and Temazepam, but one of the criticisms of the Sanford Police Department in the aftermath of the shooting is that they did not perform a drug test on Zimmerman so there's no way to know if they would have had any influence over his behavior.