This is not "a fact." It is the story told by Mr. Zimmerman. It is a contention, not a fact.
It is a fact there was a fight. How that fight started we do not know. It is likely, based on witness testimony, that Zimmerman was losing the fight when he fired and was indeed in reasonable fear of death or great bodily harm at that point.
But there are a number of things Zimmerman could have done to precipitate the fight, constituting assault, and therefore preventing him from claiming self defense.
Since nobody (alive) but Zimmerman is available to testify about what started the fight, we will never know what happened.
There is probably no evidence to contradict Mr. Zimmerman's testimony. This does not prove he is telling the truth, it only proves we can't prove he is lying.
If Martin were alive and Zimmerman dead, we would probably be in a similar situation. Martin would claim Zimmerman attacked him, armed, and he defended himself. We would probably be unable to prove otherwise.
Now you are making up ‘facts’.
There was no evidence of a fight, Martin didn't have a mark on him other than the gunshot wound.
It is a fact that a beating took place, and all the evidence and witnesses to that show it was one sided and all directed at Zimmerman.
Everything in the case supports Zimmerman's claim of self-defense.
There is no indication that Zimmerman was even returning blows, thus not "losing" a "fight".
If "John" and the mortician who tended to Martin's body are to believed, Zimmerman basically was attacked and did nothing more than fended off blows waiting for someone to come and help. At some point the gun discharged. The fact that there was not a round in the chamber when the police retrieved the weapon, suggests some obstruction preventing the gun to cycle normally. Typical of a close quarters struggle.
Actually, Trayvon's girlfriend DeeDee apparently did hear the beginning of the fight. There are some of her comments here
She said that Trayvon said: "What are you following me for?" to which Zimmerman replied: "What are you doing around here?" and then she surmised that the headset fell, attributing it to Zimmerman attacking Trayvon. As far as I know, she did not publicly report hearing anything else after the headset fell.
It would appear that was the time that the physical altercation started. Does it make sense that Zimmerman would attack Trayvon at this point, or that Trayvon would attack Zimmerman? Remember, Zimmerman had the police coming. Zimmerman reported that he went for his phone. Perhaps Trayvon thought he was going for a weapon, and decided to go on the offensive.
Not true. Instead of talking generally, let's go to the actual Florida law. Chapter 776 (Justifiable Use of Force) of Florida Statutes existed before passage of the Florida Stand Your Ground Act in 2005, but it's where the provisions of the SYGA were incorporated into existing Florida law.
The Stand Your Ground Act contemplated limited situations under which an aggressor could still use deadly force or force likely to result in great bodily harm, and be justified in doing so. Here's the link to the entire Chapter 776, but concentrate on Florida Statutes 776.041(2).
Even under common law, it's not accurate to say as a generalization that a party who commits assault can never claim self-defense. For example, under a standard application of common law, the assailant can stop the fight, achieve clear physical separation, and state clearly an intent to cease fighting. The assailant still has liability for the initial assault. However, if the other party continues fighting at that point, then the original assailant can practice and claim self-defense from that point forward.
Those elements are incorporated by statute in Florida Statutes 776.041(2)(b) - but allow the use of deadly force without retreat, which often is not permitted at common law without retreat.