Or stolen by a passerby.......................
If the gun was stolen by a passerby then the case would remain open trying to find the gun. That would be awfully inconvenient for the Arkancide team. If the gun was carried off by one or more African Swallows that got tired and dropped it in the middle of the Atlantic Ocean then case closed.
Yeah, I had that thought, too. (Stolen by a passerby).
But I can’t imagine anyone finding that body and the gun thinking, “Yeah, I probably should report this suicide, but instead I’ll steal the gun - then authorities will look for it and if I’m found with it I’m a murder suspect. Yeah, I’m taking it!”