One of the few things that GTA V is often called out on is its unrealistic wanted system. Committing any kind of crime instantly draws the ire of law enforcement. If you are out in the middle of the desert with not another soul nearby and shot the hostage you dragged out there unseen with a silenced pistol, the police will be on your ass within minutes. Somehow they will know you did something, they'll know that you did something and they will pinpoint your exact location.
Strangely enough an older Rockstar game already had a more functional and realistic system in place. Why GTA V didn't simply lift the feature over from RDR like this modder did is beyond us. The way Red Dead Redemption's witness system worked was that other NPC's had to witness a crime and report it before the authorities went after you. The player had a chance to catch and "silence" the witness before they alerted anyone, and thus a wanted level could be avoided.
Well established modder GTATerminal also came to the conclusion that this is a better system than the omniscient police found in the game by default. His version sees the witnesses phone the police if you're a bad boy around them. Currently the only way to prevent a wanted level is to murder the witnesses, however a future update will feature a bribe option as well as a lower witness rate by using silencers.
Several mods affecting police behavior and the game's response to crimes have been created over the months, as this is one of the few areas in which GTA V has been getting constant criticism. While it is in keeping with traditional GTA gameplay, the system is dated and unrealistic.
What changes would you make to GTA 5's crime system?