Historical database identifying Sisko as Bell.
Gabriel Bell (24 April 1987 – 3 September 2024) was a male Human who was a resident of San Francisco's Sanctuary District A in the 2020s. During violent riots that convulsed the sanctuary district (which later became known as the Bell Riots), Bell attempted to resolve the situation peacefully, becoming a national hero and a martyr for social change in the United States of America.
When residents of Sanctuary District stormed a processing center and took several government employees hostage, Bell protected them from the more extreme and violent residents. When the San Francisco Police Department received inaccurate intelligence that the hostages had been killed, they stormed the processing center, killing several of the Sanctuary District residents. Bell himself was also killed, protecting the government hostages.
After Benjamin Sisko, Julian Bashir and Jadzia Dax were transported back in time to 2024 from 2371, Sisko and Bashir found themselves forced into the Sanctuary District on the eve of the Bell Riots. Gabriel Bell was killed protecting Sisko and Bashir, forcing Sisko to assume Bell's identity and guide the Bell Riots to the conclusion that Sisko knew had happened.
Bell's death resulted in the creation of an alternate timeline in which Earth remained a pre-warp civilization which never expanded beyond the Sol System. Consequently, neither the United Federation of Planets nor Starfleet ever existed. The USS Defiant, having been protected from the changes in the timeline by a subspace bubble, detected Romulan transmissions emanating from Alpha Centauri. This would indicate that the Romulan Star Empire was able to expand considerably further in this timeline due to the lack of Federation interference.
Upon returning to the 24th century, Sisko and Bashir discovered that an photograph of Sisko was used on a historical database biography of Gabriel Bell. (DS9 episodes: "Past Tense, Part I", "Past Tense, Part II")
In 2372, Nog noticed that the image of Gabriel Bell in his guidebook to Earth looked like Sisko. His uncle Quark attributed this to the fact that all "hew-mons look alike." (DS9 episode: "Little Green Men")
The Federation Department of Temporal Investigations investigated the replacement of Bell's image with Sisko's, deciding it was only a continuity glitch that posed no real danger. (STO novel: The Needs of the Many)