Here is the text of the affidavit filed by the prosecution in the Zimmerman case. The facts in the affidavit establish probable cause for the 2d Degree Murder charge.
It is short, but refers to the phone call with a "friend" in which Trayvon said he was being chased and his mother identifying his voice screaming for help. Here are some excerpts as reported by the Boston Globe.
"During this time, Martin was on the phone with a friend and described to her what was happening," the affidavit said. "The witness advised that Martin was scared because he was being followed through the complex by an unknown male and didn't know why."
And this,
"When the police dispatcher realized Zimmerman was pursuing Martin, he instructed Zimmerman not to do that and that the responding officer would meet him. Zimmerman disregarded the police dispatcher and continued to follow Martin who was trying to return to his home."
Most importantly, is this
"Zimmerman confronted Martin and a struggle ensued," prosecutors said in their account.
This last statement is critical because, as pointed out
in this article the Stand Your Ground law has a completely different standard for someone who initiates a confrontation.
Here is the relevant section,
The fact that Zimmermann pursued Trayvon Martin clearly suggests that he provoked whatever subsequently transpired. And this section goes on to say that if you provoke the confrontation then you cannot use force unless you have retreated and the person is still attacking you with overwhelming force. Here is the relevant portion of that section,
776.041 Use of force by aggressor.—The justification described in the preceding sections of this chapter is not available to a person who:
(1) Is attempting to commit, committing, or escaping after the commission of, a forcible felony; or
(2) Initially provokes the use of force against himself or herself, unless:
(a) Such force is so great that the person reasonably believes that he or she is in imminent danger of death or great bodily harm and that he or she has exhausted every reasonable means to escape such danger other than the use of force which is likely to cause death or great bodily harm to the assailant; or
(b) In good faith, the person withdraws from physical contact with the assailant and indicates clearly to the assailant that he or she desires to withdraw and terminate the use of force, but the assailant continues or resumes the use of force.
The evidence indicates that Zimmermann initiated and provoked this incident. Here is no indication he retreated. There is no indication that he was faced with force that likely to result in his death or great bodily harm.
This section is why it is likely the Prosecutors think they will defeat a stand your ground defense motion when/if it is presented. That motion will be heard before the trial proper.