Marg Helgenberger
Marg Helgenberger will be leaving the "CSI" cast and her last episode airs Wednesday. Her character, Catherine Willows, is leaving the Las Vegas crime lab for a federal job. REUTERS/Mario Anzuoni

Update: Marg Helgenberger: A Look at Catherine Willows' Last 'CSI' Episode [VIDEO]

Marg Helgenberger has handed in her badge and is leaving the CBS hit show CSI next week.

After 12 seasons, Helgenberger, who plays CSI Catherine Willows, will make her exit in a two-part episode. The first aired Jan. 18 and the other will air on Jan. 25.

Helgenberger has a star in the series since it began in 2000, collecting fingerprints, swabbing mouths, analyzing blood spatter and examining exit wounds.

But Helgenberger told CBS This Morning that she is leaving CSI because she felt it was time.

I felt the need to kind of step back, because I had been playing this character for 11 and a half years, to reassess and regroup and I'm -- as scary as that is -- I'm also very excited about the great wide open, the future and all the possibilities, Helgenberger said.

Helgenberger told The Associated Press that she is looking forward to the time off. The 53-year-old star has also said that she is looking forward to hiking with her dog and looking for work.

Helgenberger, who has become one of the highest-paid actresses on television, also has her eyes set on Broadway. The stunning actress said she is also willing to return for a special episode or two some time in the future.

Oh, absolutely, in fact that was one of the reasons why it was a little easier for me to leave the show because the producers said to me practically every day the door is wide open, she told The AP. If I'm available and I'm up for it you betcha.

Thinking about leaving for a long time

Last year, Helgenberger told Entertainment Weekly that she has been thinking about leaving or some time now. The CSI team said their final goodbye to Helgenberger last month.

Series creator Anthony E. Zuiker and Executive Producer Carol Mendelsohn were all on set for Helgenberger's goodbye when she wrapped her 263rd episode.

I've been thinking a lot about this moment for a very long time, Helgenberger told the cast who had gathered for the send. From the bottom of my heart, thank you for the time of my life.

Helgenberger made everyone fall in love with her character Catherine Willows, who was introduced in the pilot script as a CSI-3, single mother and ex-stripper.

Helgenberger has told Charlie Rose and Gayle King that some of the female producers had thought about changing that backstory once the show got put on the air.

I said, 'No, no, no, this is a woman who, that journey she took is much different than most people who go into law-enforcement, and I thought it really informed the character and the story, Helgenberger said. So I'm glad I stood up for my stripper-dom.

Actress Elisabeth Shue will be joining the CSI cast as Helgenberger's replacement. Shue's first episode will air on Feb. 15.

Still Helgenberger tells fans, You haven't seen the last of me.