Here's a nice way to create your own evidence: an old-school revolver that has a camera under the barrel, set to snap a shot every time you pull the trigger.
Made in 1938, you've gotta wonder why this didn't catch on. I mean, sure, no criminals would want to create evidence of their evildoing. But what about cops? Wouldn't it be good for them to have photos of whatever they were aiming at? These days we've got helmet cams that do the same thing, but this seems like it was way before its time.