Marg Helgenberger: 'CSI' Alum Returning for 300th Episode

The milestone 300th episode of the long-running drama, "CSI: Crime Scene Investigation," will feature the return of original cast member Marg Helgenberger.

An original cast member, Helgenberger spent 12 seasons playing Catherine Willows. Her alter ego rejoins the team to help solve a 14-year-old cold case murder.

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"We will flash back 14 years to seminal moments that show Catherine, Nick, Sara, Greg and Ecklie as they were, [and how that] informed the evolution of the characters now," executive producer Don McGill told Inquisitr.com. "It's going to be a really fun episode, very emotional, that honors 14 years of CSI."

Helgenberger left the show in 2012.

"We were just really excited to have Marg come back because, obviously, she's such an important part of the history of CSI...And she was super excited," McGill said. "It was kismet!"

Her return was originally announced in August, but the episode is scheduled to air Wednesday night at 10 p.m. In a TV Guide interview, Helgenberger listed a few of her more memorable episodes. 

"CSI" was produced by Jerry Bruckheimer and premiered in 2000. Set in Las Vegas, the team collects evidence from murder scenes to solve crime. The show's popularity has led to spinoffs including "CSI: Miami" and "CSI: New York."

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The original starred William Peterson as the head of the forensic team, and Ted Danson and Elizabeth Shue now head the cast. Actors George Eads (Nick Stokes) and Paul Guilfoyle (Jim Brass) are the only main characters who have been in the show from the first season.

Beyond her CSI appearance, Helgenberger returns to series television in CBS' "Intelligence," which co-stars LOST alum Josh Holloway.