As to motivations for murder

[Ocelot II]

2. Quite true - most assassinations in modern times have not been overtly political,

at least in the sense of having been motivated by clealy conservative vs. clearly liberal ideologies. Guiteau shot Garfield because he had campaigned for Garfield and thought he was owed a government job that he didn't get. It's still not clear why Oswald shot JFK; some think he did it so Cuba would accept his defection. It's fair to say that any kind of assassination, even ordinary murder, is not the act of a mentally stable person. The killer of Melissa Hortman focused on Democratic politicians but for warped and extreme religious reasons.Tyler Robinson seems to have been sucked into some kind of completely online world that doesn't recognize conventional politics at all. It's a big mistake to look at these incidents as one political side vs. the other. It's not binary like that, and there's a whole lot of crazy involved.