Some of them, we don't know who did them at all (e.g. MLK).

But even if that was the case, it's not difficult to manipulate a "crazy" to do something, especially if you have both crazies and guns in abundance in a country.

It would be a nice way to avoid blame for the whole thing, and you can even have some mafia figure/ex-cop collaborator kill them afterwards, before said crazies ever get to go to trial for the first murder.

>you have to come up with some evidence otherwise it's just conspiracy theorizing

You think there's much evidence in e.g. banana republic political murders too, even those where still everybody knows the government or some mogul with special interests ordered them?

It's not difficult to say it's not difficult. Again, it's a completely evidence-free claim.

You think there's much evidence

There isn't any evidence the government is taking out hits on politically inconvenient figures in the US. "There can't possibly be any evidence, look at some other (vaguely described, non-specific place/event) where there is also no evidence, QED" is pretty much classic conspiracy-theorist logic (if you can call it that).