I believe Zimmerman has claimed that he followed Martin, but that he was walking back towards his car when Martin approached him, they "exchanged words", and then Martin hit him. See the paragraphs below the heading "One-minute gap" here:http://articles.orlandosentinel.com/2012-03-26/news/os-trayvon-martin-zimmerman-account-20120326_1_miami-schools-punch-unarmed-black-teenager
That's is allegedly Zimmerman's account of the events that led to the shooting.
Let's assume for a moment that what is described there is true. Under that scenario, did Zimmerman "seek a confrontation"? If he was following somebody whom he considered suspicious, but didn't approach the person and didn't confront that person, is that seeking a confrontation?
Perhaps yes, perhaps no. A reasonable person might wonder why somebody was following them. Zimmerman certainly could have not followed Martin, and simply made the report to the police by phone.
If we further suppose it's true that Zimmerman was actually walking back to his car when Martin approached, then it seems pretty hard to argue that he "sought a confrontation" at that point. In the absence of a third-party witness, how can we ever know whether he was walking back to his car or not?
I think it's really hard to have any kind of informed opinion about this case at this point, because so much of the information that has come out is biased, incomplete, or fabricated. Even something that appears to be reasonably objective may not hold up to scrutiny. For example, the newspaper piece I linked above says, "On Feb. 26, when Zimmerman first spotted Trayvon, he called police and reported a suspicious person, describing Trayvon as black, acting strangely and perhaps on drugs."
But, the 911 tapes actually show that the dispatcher asked Zimmerman a direct question about the race of the "suspicious person", and Zimmerman answered it. So, depending upon how you read that sentence, you may infer that Zimmerman had racial motivations, because he "described Trayvon as black", but does that inference change when you realize that he was answering a direct question?
I think there are clear problems with the presumption that the use of force in self-defense was justified, but there are similar problems with the opposite presumption. What if, in a completely hypothetical scenario, Zimmerman was walking down the street, was confronted and assaulted by Martin, and Zimmerman shot Martin under circumstances that any of us would consider absolutely justified? If there were no witnesses to the confrontation other than the two parties involved, and one is dead, then would you argue that Zimmerman should be presumed to have acted criminally? How could he ever show that he didn't?
Very difficult stuff, and not nearly as clear cut IMO as the news media seem to want it to be, on either side.