The whole gang is back for the CSI: Crime Scene Investigation series finale, and Marg Helgenberger took time out to reminisce over the show's triumphant run in a sit-down with ET.
"When it came time to do this episode -- which I didn't quite anticipate happening because CSI was going to go on forever, right? -- but I was happy that they brought me back," Helgenberger told ET. "There were some emotional moments in particular. I saw my teammates just gathering up all the evidence of body parts and you-name-it and I just was moved by that."
WATCH: A Look Back at 15 Years of 'CSI' Before Its Final Bow
It's all coming to an end on Sunday after 15 seasons and more than 300 episodes. While the actors are saying goodbye to the show, that doesn't mean they have to say goodbye to each other, and there are definitely some co-stars that Helgenberger hopes to work alongside again.
"[William Petersen] and I did have a wonderful chemistry together and a mutual love and respect for one another," Helgenberger admitted. "I hope we get to do that again at some point down the line and with all the other actors as well. We'll stay in touch for sure."
The show featured many of today's biggest stars before they became household names, from Emmy winner Viola Davis, who guest-starred in 2002, to Taraji P. Henson, who appeared in 2006, to Dakota Fanning, who was just five when she was a guest in 2000.
The show also provided guest roles for musicians who were already famous, such as Taylor Swift in 2009 and Justin Bieber in 2010, who both left an indelible impression.
MORE: 'CSI' Is Officially Ending After 15 Years
For Swift, it was her first acting job, and for Bieber, it was before his bad boy persona took a foothold.
"Honestly, he was lovely to me," Helgenberger recalled. "I think some of the crew had issues with him, but they should talk about that, not me."
Over the past 15 seasons, CSI has amassed a large ensemble with the likes of Petersen, Helgenberger, Gary Dourdan, George Eads, Eric Szmanda, Jorja Fox and Paul Guilfoyle among the series' original cast members. The most recent season was led by Ted Danson and Elisabeth Shue. CSI was a boon for CBS when it debuted in 2000, helping boost the network's place among the broadcast networks and launching numerous spinoffs, including CSI: NY, CSI: Miami and CSI: Cyber.
PHOTOS: The 10 Most-Watched Series Finales Ever
Watch the video to see Helgenberger's first interview with ET in 1985.
The CSI two-hour sendoff airs Sunday at 9 p.m. ET/PT on CBS.