In the hypothetical situations you listed, it may have been suspected that there was some communication that had taken place on the computer in order to accomplish/attempt the listed crimes.
I listed no hypothetical situations at all. And no, there's no requirement at all to suspect such communication. Everything you have is subject to discovery.
In the case of a shooting, that includes your gun collection, your reloading bench and data, your targets, your bookshelf, and yes,
your computer.
I don't know if you have ever received a subpoena, but I have.
In a spur of the moment self-defense shooting, there is no premeditation and no reason to think there would be anything related to a self-defense shooting gone wrong on the defendant's computer.
One: How is anyone to conclude that a shooting is a "spur of the moment self defense shooting"? That's the question.
Any shooting could involve negligence, an accident, consensual combat, premeditated murder, whatever. That is what the investigators and he judicial system will try to determine. If the field evidence is clear and supports a claim of self defense, fine. If not, that's where the fun begins.
By the way, premeditation is not a prerequisite for conviction for a crime.
Two: What do you think constitutes a "self defense shooting gone wrong"?
There's a shooting. The shooter claims self defense. Maybe there's clear evidence to support his claim. Maybe not. If not....it's
all open to investigation. Everything.
Someone shoots another person. Claims he fired in self defense. No witnesses. Why would anyone believe the story? Wouldn't anyone make that claim?
I really do not think you read the information on the link that pax provided.
Read it. Heed it.
If that doesn't help, contact an experienced criminal trial lawyer.
In the mean time, understand that
everything you put in the mail or in email or on the internet is discoverable and is permanent and cannot be retracted.