Spoiler Alert: This article contains spoilers for CSI and CSI: Vegas.
The CBS limited series CSI: Vegas is a sequel to CSI, which ran for 15 seasons on the network between 2000 and 2015. Though the 2021 drama includes many new characters who are working in the Las Vegas Crime Lab, it also features a few familiar faces from the original series.
While fans of CSI were thrilled that Sara Sidle (Jorja Fox), Gil Grissom (William Petersen), David Hodges (Wallace Langham), and Jim Brass (Paul Guilfoyle) each returned to the new series in some capacity, many have noted the absence of Catherine Willows (Marg Helgenberger).
The investigator appeared in the first 12 seasons of CSI, before she took a position with the FBI. In the 2015 series finale, Catherine was named as the Director of the Las Vegas Crime Lab.
As viewers learn in the first episode of CSI: Vegas, Maxine "Max" Roby (Paula Newsome) has taken over Catherine's position, leading many to wonder if she will return to the sequel show at some point.
Where is Catherine Willows on 'CSI: Vegas'?
In the pilot of CSI: Vegas, "Legacy," two characters from the original series, Sara and Jim, discuss Catherine's whereabouts. They confirm that she can't help Jim in person after his brutal attack because she is visiting her grandchild overseas.
"Catherine has rolled out a red carpet," Sara says in the episode. "She would be here, you know that, if she could."
"Yeah, she's got a little grandbaby in Dublin," Jim responds.
The two do not mention their former colleague again, so it's unclear if Catherine lives in Ireland full-time, or if she will possibly be returning stateside in the future.
Because Catherine is still alive in the limited sequel series, there is always potential for the character to come back. Since Max has taken over Catherine's position, it could be interesting to see the two interact with one another or to maybe work together.
However, it does not appear as if there are any concrete plans for Marg to reprise her CSI character — though the actress has certainly teased a cameo on her Instagram feed.
"#tbt I keep reading about a #CSI reboot... #CatherineWillows," Marg wrote in the caption of a post on Sept. 16, just a few weeks before the show premiered.
What is Marg Helgenberger up to today? The actress is active on social media.
While fans are missing Marg on their screens for CSI: Vegas, they can keep up with her latest acting gigs and life updates online. The actress most recently appeared in All Rise as Lisa Benner, in Under the Dome as Christine Price, and in Intelligence as Lillian Strand.
Marg's latest film role was as Hannah in the 2019 drama, A Dog's Journey.
In addition to sharing behind-the-scenes photos on her Instagram feed, Marg periodically posts pictures with her son, Hugh Rosenberg.
CSI: Vegas airs on Wednesdays at 10 p.m. ET on CBS.