I actually thought things like that could be done, imagine someone just went hiking came across 2 people and with a gun they had wiped clean and had 2 bullets and shot one of them in the head twice then threw the gun at the person with them, naturally they'd probably grab the gun or pick up the gun and now their friend/wife/husband/parent or whoever is dead shot with their fingerprints the only ones on the gun.

It would be hard to explain how you didnt do it. Police would be like "so someone just walked up killed your wife and threw the gun and you picked it up", "90% of people are killed by someone they know", "the persons mother said that you both argue all the time", "we know you have been to a gun range before and watch hunting programmes on TV" etc anything would be brought up that before didnt mean anything.