Highlights from the Twelfth Episode of Season 12 of CSI

Sara Sidle (Jorja Fox) checks her phone while being engaged in conversation in this scene in Marg Helgenberger's last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Members of the CSI team from left to right Greg Sanders (Eric Szmanda, left), Morgan Brody, (Elisabeth Harnois), Nick Stokes (George Eads) and Sara Sidle (Jorja Fox, right) all react to what Captain Jim Brass (Paul Guilfoyle, standing) has to say in Marg Helgenberger's last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Behind-the-scenes: Marg Helgenberger while the next scene is being set up in this behind-the-scenes photo from her last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Sonja Flemming/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

This is a very emotional moment for Catherine Willows (Marg Helgenberger) in her last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Morgan Brody (Elisabeth Harnois, left), Sara Sidle (Jorja Fox), Nick Stokes (George Eads) and Greg Sanders (Eric Szmanda) all look concerned as they leave the lab in this scene from Marg Helgenberger’s last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Catherine Willows (Marg Helgenberger) stands beside Laura Gabriel (Annabeth Gish) and Agent Pratt (Matt Lauria) in this scene from her last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Catherine Willows (Marg Helgenberger) on CSI: CRIME SCENE INVESTIGATION. Marg Helgenberger's last episode. Photo: Sonja Flemming/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Marg Helgenberger on her last day on the set of CSI. Photo: Sonja Flemming/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Marg Helgenberger is applauded in the CSI set. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Marg Helgenberger receives her name plate knowing millions of fans across the world will miss seeing her on CSI. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Catherine Willows (Marg Helgenberger, left) stands in the doorway along side Laura Gabriel (Annabeth Gish) in this scene in her last episode on CSI: CRIME SCENE INVESTIGATION

Catherine Willows (Marg Helgenberger) walks through the walls of CSI one last time in her last episode on CSI: CRIME SCENE INVESTIGATION,

Catherine Willows (Marg Helgenberger) hugs one of her longtime co-workers (Nick Stokes (George Eads) as members of the CSI team look on in her last episode on CSI: CRIME SCENE INVESTIGATION

Catherine Willows (Marg Helgenberger) hugs one of her longtime co-workers (Nick Stokes (George Eads) as members of the CSI team look on in her last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

This is a very emotional moment for Catherine Willows (Marg Helgenberger) in her last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

This is a very emotional moment for Catherine Willows (Marg Helgenberger) in her last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Catherine Willows (Marg Helgenberger, left) and D.B. Russell (Ted Danson) in Helgenberger’s last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.

Sara Sidle (Jorja Fox, left) and Nick Stokes (George Eads) are about to be hit with some news in Marg Helgenberger’s last episode on CSI: CRIME SCENE INVESTIGATION. Photo: Monty Brinton/CBS ©2011 CBS Broadcasting Inc. All Rights Reserved.