The Senior Supervisor is the one who as worked as a supervisor the longest:

• Season 1-9: Gil Grissom
• Season 9-12: Catherine Willows
• Season 12- present: D.B. Russell

Office

This is the office of the highest ranked supervisor in the Las Vegas Crime Lab. It formerly belonged to Gil Grissom from season 1-9 in CSI:. As director, Conrad Ecklie offered this office to Catherine Willows after Gil resigned but she declined. In season 9-12, this office belonged to Nick Stokes.