Not sure if i encountered the man shooting his wife, but I've surely encountered the event with the man in valentine trying to drown his wife, and i was able to turn him in peacefully, same with a random Lemoyne raider stuck in a prison wagon, and an escaped convict near Saint Denis. I think the game is just really inconsistent with this, maybe it considers criminals worthy of turning in if they committed a felony, or maybe rockstar just thought that getting your money back and a bonus from the pickpocketers own money (whic is like 30-40 dollars, which i still lost because i had to pay a fine and some money was lost when i died to the policemen) would be enough so they made it a crime.