“Dead Man Walking” first aired February 20, 2007.

With a plot stripped from the current events surrounding the decidedly Cold War murder of former Soviet operative Aleksander Litvinenko, the NCIS team is asked to investigate the poisoning murder of an American nuclear inspector. The twist is the inspector himself is requesting the investigation.

International Atomic Energy Agency (IAEA) inspector Navy Lt. Roy Sanders (Matthew Mardsen) enters NCIS headquarters with Special Agent Tim McGee (Sean Murray) (wearing a $2000 Armani Jacket – the spoils of his writing career) requesting Special Agent Leroy Jethro Gibbs (Mark Harmon) to investigate his murder while dramatically pulling out a clump of his own hair and showing it to Gibbs during his request. Mossad Agent Ziva David (Cote de Pablo) begins the first segment with a strange déjà vu regarding Lt. Sanders. Ziva seems to know him from somewhere. Gibbs enters and reveals that Sanders is still being examined by NCIS Medical Examiner Dr. Donald "Ducky" Mallard (David McCallum) and his thought is Lt. Sanders is suffering from radiation poisoning, but the source is yet unknown. Ziva tries to think of where she knows Lt. Sanders.

Fearing the McGee has also been exposed, he is forced by Forensics Specialist Abby Sciuto (Pauley Perrette) to strip completely so that he and his clothes can be analyzed for radiation. Abby wants his Armani jacket also, promising she will not harm it. Meanwhile, Ducky has a living client for a change who is able to talk back to him. Blood samples are drawn and sent to radiobiology for analysis. However, Ducky and Lt. Sanders believe that he has been poisoned with an alpha emitter (such as Polonium-210 as in the Litvinenko case) rather than beta- or gamma- emitters (such as Uranium-238 and Plutonium-239). Alpha particles can be stopped by the dead skin cells on the epidermis, but when ingested can wreck havoc on internal organs).

Ziva is ordered to accompany Lt. Sanders to Bethesda, where he is being transferred. Gibbs is hoping that this will jog her memory of where she has seen Sanders. Sanders registers what looks like flashing recognition before Ziva launches into her attempts to make a connection. Make a connect they do, but it is just Ziva’s dumb luck. The scene breaks to Gibbs and Special Agent Tony DiNozzo (Michael Weatherly) visit IAEA headquarters and meet Sanders’ colleagues Mark Sadowski (Marc Vann) and Diane Russio (Kate Norby) and the harried secretary Holly Stegman (Erin Torpey). Gibbs appraises them that Sanders was poisoned with radiation. DiNozzo searches Sanders’ desk finds a picture that proves to be his sister. The radiobiology lab returned the results showing that Sanders was poisoned with Thallium no longer than 72 hours previously. This send the NCIS team into an investigation of where Sanders had been in the previous 72 hours.