When I was in undergrad, we had to take a class in the counseling department. We had a little 'exercise' a scenario in which we were asked who was responsible for the fate of a woman who was killed.
The woman had crossed a lake by boat to visit people she knew. There were 3 houses. In one house there was a person who did not know her. In another was a person who knew her but did not love her. In the third house was a person who knew her and loved her. A storm came up when she started home and the man who ran the boat would not take her back across the lake. He said it was against policy to push off in a storm. She wen to the house where the person loved her and he would not take her in. Then she went to the house where the person knew her but did not love her and he would not take her in either. Nor would the person at the house where the person did not know her. She had two choices. She would have to decide to go around one side of the lake where there were cliffs or around the other side which was wooded. She chose to go through the woods and was killed by a maniac.
The prof then asked who is responsible for her death. When one person kills another, a lot of people have a problem with the person not being held to be accountable. But the person who killed her was a maniac and, therefore, not responsible. No problem with the bureaucrat. People don't blame bureaucrats. No problem at the house where no one knew her. But some had a problem with the other two not taking her in, but they were under no obligation to her.
But she chose to cross the lake, she chose to stay until the storm came up. She chose to go through the woods. The choices were all hers. So she was the only one who could be held responsible.
There was a point in time when Zimmerman had lost Martin and Martin could have gone home, but he did not. He came back and assaulted Zimmerman. Had Zimmerman been the one who died, and he well could have, Martin would have been tried as an adult in the killing. Martin made all the choices here, just like the woman in the story. Martin is responsible. Not Zimmerman.