NCIS - Season 3 - Eps 20: Untouchable
When a Pentagon cryptographer is found dead, the NCIS team has to discover whether the person was or wasn't a Pentagon mole, and if the person committed suicide. As the investigation continues, the team discovers that the person wasn't alone when she died, so someone must have murdered her. So, the team has to find the person, a mole, who murdered the cryptographer.
About NCIS

Title: NCIS
First Air Date: 2003-09-23
Last Air Date: 2025-03-31
Status: Returning Series
Rating: 7.6/10 (from 2334 votes)
Language: EN
Seasons: 23
Total Episodes: 487
Network: CBS
Genres: Crime, Drama, Action & Adventure
Production Companies: Paramount Television, Belisarius Productions, CBS Studios
Synopsis
From murder and espionage to terrorism and stolen submarines, a team of special agents investigates any crime that has a shred of evidence connected to Navy and Marine Corps personnel, regardless of rank or position.
Cast

Sean Murray
Timothy McGee

Wilmer Valderrama
Nick Torres

Katrina Law
Jessica Knight

Brian Dietzen
Jimmy Palmer

Rocky Carroll
Leon Vance

Diona Reasonover
Kasie Hines

Gary Cole
Alden Parker