In this year, Doc happily accepted his new life working as a blacksmith in the Old West, buried the DeLorean in the Delgado Mine (along with repair instructions) and sent Marty McFly, who was stuck in 1955, a letter via several generations of Western Union. However, a week after writing the letter, Doc was shot in the back at the Hill Valley Festival with a derringer wielded by Buford Tannen and died two days later, on September 7.
Doc was laid to rest in the Boot Hill Cemetery where his grave was discovered by Marty and Doc's younger 1955 counterpart on November 14. Marty subsequently decided to disregard the instructions in Doc's letter to return to 1985 and destroy the time machine, and instead travel back to the Old West and bring Doc home.
The events of this alternate timeline were subsequently overwritten by those of 1885.
- Back to the Future Part III (in Doc's letter)