@spendius,
Oh, I think the man is definitely experiencing rather significant psychiatric problems, but he had those problems long before he killed Trayvon Martin, they've just gotten worse lately.
His not letting the police in, and instead calling 911, as a way of getting out his "side of the story" could not have been a more manipulative tactic--this man is a schemer. He came up with a story that would blame and discredit her, or so he hoped, and by barricading the door, he gave himself time to possibly alter the crime scene so it might better fit his version of events.
The problem is, his "story", as expressed in his extremely calm, matter-of-fact 911 call, really doesn't sound credible or plausible at all. And, because his 911 call was recorded, and it's been played in the media, he's stuck with that version now.
What Zimmerman likely didn't know was that his girlfriend had been texting a reporter for three weeks, describing his disturbed and volatile and threatening, and vindictive, behaviors, her fears of him and of what he might do to either her or himself, and her desire and efforts to get him to go for psychiatric help, and her wish to separate from him because she was afraid. And because she had established some "documentation" of what he was like, and what her life with him was like, and the fact she did want to end the relationship, weeks prior to his arrest, I think it helps to lend her story more credibility than his considerably less than plausible version of what transpired the day she called 911.
Also, he's been exhibiting a pattern of threatening behaviors toward others, like his estranged wife, lately, and when an ex-fiancée tried to break off with him in 2005, he also became aggressive toward her and she obtained a restraining order against him.
And this time, the police had no hesitancy about arresting him, so they found her credible too.
We'll have to wait to see how this unfolds in court.
But, he'll have to come up with something to explain why he stayed barricaded in the house, with the police pounding on the door, while he picked up the phone and and called 911, to tell his "story". And now he's stuck with that implausible story.