Rooney was a Human male who served in Starfleet's operations division while assigned to Deep Space 9, under Captain Benjamin Sisko, during the early 2370s. According to Jadzia Dax, Rooney was very proud to wear his uniform, and likewise proud to serve under Captain Sisko.
Rooney was an accomplished trumpet player, and was known to perform at Quark's. Sisko and Dax once heard him play there, where he had people "dancing in the aisles".
Rooney died in 2373, during a mission to the Gamma Quadrant planet Torga IV, when the runabout he was aboard was destroyed by a Jem'Hadar warship. (DS9: "The Ship")