Fernando Sepulveda was a Starfleet officer in the 24th century.
In 2367, as a lieutenant, he was the Ops Engineer for the Third Shift Antimatter Operations Unit on the USS Enterprise-D. He was listed as being on duty in the Engineering Division Duty Roster. This roster was on display via the desktop monitor in the ready room. (TNG: "Suddenly Human", okudagram)
In 2371, he was a crewmember aboard the USS Voyager. He was among the crew stranded in the Delta Quadrant, when Voyager was forcefully brought there by the Caretaker.
In 2372, as a lieutenant, he was listed on the Planetary Geosciences Division duty roster. (VOY: "Parturition")