Media playback is unsupported on your device Media caption CCTV footage of Trayvon Martin at 7-Eleven

A Florida neighbourhood watch volunteer who shot an unarmed black teenager had a bloody nose and a cut on his head, according to police reports.

The documents were released to defence lawyers for George Zimmerman, who is accused of second-degree murder over the 26 February killing in Sanford.

The file includes autopsy evidence that traces of a cannabis ingredient were found in Trayvon Martin's system.

Mr Zimmerman, 28, maintains he shot the 17-year-old in self-defence.

He was not arrested for several weeks after the shooting because he invoked Florida's "stand your ground" law, which allows deadly force in the face of a serious threat.

The racially charged case, which sparked nationwide protests, has divided the US.

'Fistfight'

Police tried without success to revive Trayvon Martin after finding him face down in the grass with a single wound to the chest, according to the police reports.

Several officers who arrived at the scene noted that Mr Zimmerman had injuries.

Image caption Police photos show injuries to George Zimmerman's face and head

Officer Timothy Smith said: "I could observe that [Mr Zimmerman's] back appeared to be wet and he was covered in grass, as if he had been laying on his back on the ground. Zimmerman was also bleeding from the nose and the back of the head."

Another officer, Jonathan Mead, said in his report that the neighbourhood watchman "appeared to have a broken and bloody nose and swelling of his face".

A medical assessment found a 1in laceration to the back of Mr Zimmerman's head.

"All injuries have minor bleeding," wrote paramedic Michael Brandy.

The report includes a number of witness statements, including one from a resident who said she saw two men chasing each other, followed by a fistfight. Then she heard a gunshot.

Another resident told police he saw "the black male mounted on the white or Hispanic male and throwing punches 'MMA (mixed martial arts) style'".

The resident said he shouted to the struggling pair that he was going to call the police, before he heard the "pop" of a gunshot.

Another resident is quoted by police as saying: "I opened door and saw a guy on the ground getting hit by another man on top of him… (guy getting hit on ground was wearing red [an apparent reference to Mr Zimmerman] calling out for help)".

'Ultimately avoidable'

The file notes that Mr Zimmerman had previously called police several times to report "suspicious persons, all young black males" in the neighbourhood.

Trayvon Martin's family and supporters accuse Mr Zimmerman of racially profiling the teenager, who was wearing a dark-grey hooded top at the time.

Also included in the documents released on Thursday was a statement from investigator Christopher Serino, who recommended Mr Zimmerman be charged.

He told prosecutors in March that the fight was "ultimately avoidable" if Mr Zimmerman had remained in his vehicle and waited for police to arrive.

Police interviews with acquaintances of the neighbourhood watchman include an unidentified woman who said she avoided Mr Zimmerman.

According to the Associated Press news agency, the woman said: "I know George, and I know that he does not like black people. He would start something. He's very confrontational. It's in his blood. We'll just say that."

The documents also confirm previous media reports that Trayvon Martin was visiting Sanford because he had been suspended from his Miami high school for cannabis possession.

Medical examiners found THC, the psychoactive ingredient in marijuana, in the teenager's blood and urine, according to an post-mortem report among the tranche of documents released on Thursday.