I said "believe" precisely because I don't know for a fact. Nobody does. Yet many people seem quite confident to declare that his murder was caused by "white supremacy." If BLM ever say that they "don't know" whether racism had anything to do with a police shooting, let me know.
Let's put it this way; there is no evidence to suggest that Tyre's murder had anything to do with racism. There is no reason to believe his murder was related to racism. Again, I know that racism exists. that doesn't make it the explanation for every issue.