CBS is saying goodbye to the show that turned the network’s fortunes around some 15 years ago. “CSI: Crime Scene Investigation” will wrap its 15-season run in September with a two-hour finale that will reunite original stars William Petersen and Marg Helgenberger.

The finale will air Sept. 27 and feature other returning cast members who have been on the forensic procedural over its run. Ted Danson, the current “CSI” star, will relocate to the latest spinoff, “CSI: Cyber,” opposite Patricia Arquette.

“It’s easy to take it for granted,” said Kelly Kahl, CBS senior exec VP. “This is one of the strongest and longest-running dramas in TV history.” He noted its importance to CBS: “This was one of the shows that reversed our fortunes and put us in the right direction.”

“CSI” was a sleeper hit for the Eye in its debut in the fall of 2000. The show’s cinematic style and fast-paced storytelling helped launch a new wave of procedurals. It spawned two spinoffs, “CSI: Miami” and “CSI: New York,” that enjoyed healthy runs.

“CSI” was also the show that put Jerry Bruckheimer’s TV division on the map. It was created by Anthony Zuiker, a newbie to TV at the time who was paired with drama vets Carol Mendelsohn and Ann Donahue after the pilot.