The 53-year-old is set to hang up her lab coat after 11 years as Catherine Willows on the long-running crime drama.
"Yes. It's nice to know because it has been such a big part of not only my career but my life; a fifth of my life. I adore everyone I work with. It's been a home away from my home; my family," she said.
Marg - who will be replaced by Elisabeth Shue - has been one of the longest serving members alongside George Eads (Nick Stokes) and Paul Guilfoyle (Captain Jim Brass) since the show debuted in 2000.
"I have a lot of feelings about it, but ultimately I'm ready, excited," she admitted.
"Especially after yesterday; I worked a 14-hour day, which went some way toward solidifying my decision! For a better way of putting it, they are getting their money's worth out of me."
The mother-of-one is looking forward to taking a break, adding: "I've already booked a beach house on the island of Kauai. I've booked a couple of weeks because I will be wrapping up my run on the show on December 7, so I'm looking forward to that and not doing a whole lot."
:: The full original series of CSI premieres on CBS Drama from December 12 at 9pm. For more information, visit www.cbsdrama.co.uk.
