If you are meaning took/stole through decietful or forceful means. I do not know how that could fall under negligence, any more than some one stealing your car and the thief having a wreck and harming someone.
I would think it safe to say there are hundreds/thousands of crimes every year in the U.S. with stolen weapons. I do not believe I have ever heard of the rightful owner of those weapons ever being prosecuted or charged for negligence. Not saying it hasn't/won't be tried. Just that I've never heard of it.
But let's not give the antis any ideas. Shhhhhhhhhhhh.