[Verginius Rufus]

If Martin was on drugs (which is what Zimmerman thought from observing him) his thought processes may not have been rational. All he had to do was go to his father's girlfriend's place--he was in no danger from Zimmerman. He chose to confront Zimmerman, taking him by surprise.

Was Zimmerman supposed to tell him, "I'm a neighborhood watchman and I'm just making the rounds to make sure no one tries to break in to any of the units"?

[Jonty30]

It is certainly possible that Martin wasn’t completely there that day, but that doesn’t change the fact that Zimmerman, imo, made an error of his own that might have changed the situation.

[House Atreides]

“If Martin was on drugs (which is what Zimmerman thought from observing him) his thought processes may not have been rational....”
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It’s unfortunate, but Martin’s thought processes that night were probably the same as they were all the time—on drugs or not. Reading the texts traffic of his that was released, he had long since lost, if he ever actually had any, any rationality that may have guided him into the better path.

He CHOSE his path that night. It ended with his death but it very well could have ended with the death of Zimmerman.