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LD50 is the fourteenth episode of NCIS: Los Angeles.


The body of a career criminal posing as a Marine is discovered, prompting OSP to investigate. They soon discover that a biochemical weapons expert suffering from Alzheimer's disease was tricked into producing a deadly toxin for an arms dealer. The team soon realize that there will be an auction at which the weapon will be sold and race against the clock to stop international terrorists from buying the weapon which could be used to launch a bio-terror attack against Los Angeles.

Episode Name OriginEdit

The name "LD50" refers to the deadly substance around which the episode revolves.


Series RegularsEdit

Actor/Actress Character Role
Chris O'Donnell G. Callen Special Agent
LL Cool J Sam Hanna Special Agent
Linda Hunt Henrietta Lange Operations Manager
Peter Cambor Nate Getz Operational Psychologist
Daniela Ruah Kensi Blye Special Agent
Adam Jamal Craig Dominic Vail Special Agent
Current Status: Missing in Action

Recurring GuestsEdit

Actor/Actress Character Role
Barrett Foa Eric Beale Tech Operator
JR Bourne Dallas Head of the local crime syndicate who previously appeared in 'Breach'

Other CastEdit

Character Actor Role
Esther Balmore Julianna McCarthy Former expert on the development of toxins, now suffering from Alzheimer's
Gage Jenson Dameon Clarke
Simon Amputuan Played by Burt Bulos Filipino arms dealer detained by NCIS
Jacobus Troyger Played by Andrew Connolly Arms dealer responsible for the auction at which the Clostridium botulinum was sold
Blond Man Played by Bru Muller
Sadiki Hassan Played by Vachik Mangassarian Egyptian arms dealer present at the auction

Real World ConnectionsEdit

Lethal Dose, 50% or LD 50, is one the measures used to indicate the dose of radiation or of a toxic substance required to kill half the members of a tested population. Other measures used to indicate the dosage include LC50 (Lethal Concentration, 50%) or LCt50 (Lethal Concentration & Time).