Luigi Mangione

There's a lot of ring cameras out there and there was a manhunt going on. You gotta remember that this dude needed to not be seen. By cameras or otherwise.

I would say he should have broken the evidence apart into smaller pieces. If the gun was 3D printed, I'm assuming he knows how to disassemble it. Dispose of each peice in a different public garbage can. Once again though, this involves going out in public a lot of times during a man hunt.

Or put it all in that one backpack, find a place where you can make a burn barrel, and set it all of fire.

Or fill the bag with some cement and throw it into a body of water.

People have been disposing of evidence for years. Keeping it all on you for 5 days, having a "manifesto" that admits guilt, and then pleading Not Guilty is suspect as fuck.