I Shot the Sheriff was a challenge planned for the Rockstar Social Club shortly after the game's release in 2010, however the original challenge was scrapped. The original reward for completing the challenge was to unlock the eight playable Marshal multiplayer characters in the Outfitter. These characters were subsequently unlocked for everyone without the challenge.
In lieu of this challenge and another scrapped challenge titled "Skin It to Win It", Rockstar instead started an XP challenge on January 18, 2011 with the reward of unlocking Xbox LIVE and PlayStation Home avatars. The announcement of this challenge, including a reference to the two scrapped challenges is in this Rockstar Newswire article.
- The name is most likely a reference to the Bob Marley song, "I Shot the Sheriff".