Which rookie CSI's death leads Jim Brass to lose the supervisor position?

Holly Gribbs’s death led Jim Brass to lose the CSI supervisor position.

Gribbs was a rookie CSI assigned to the Las Vegas night shift in the pilot episode. During her first day, she was left processing a robbery scene and was attacked by the suspect. She was shot and later died from her injuries, exposing serious failures in supervision and scene security.

Brass had been the night-shift CSI supervisor, but the department removed him from that role after Gribbs’s death. Gil Grissom then became the team’s supervisor, while Brass moved into the homicide division as captain. That change established the working relationship that defined much of the series: Grissom led the forensic team, and Brass handled arrests, interrogations and police procedure.

The character is sometimes confused with later CSIs such as Sofia Curtis, Wendy Simms or Riley Adams, but none of those characters caused Brass’s original demotion. Holly’s death is also important because it shapes Warrick Brown’s early storyline: he had left her scene to place a bet, and the department investigated his responsibility.