Martin Stillwell was the CEO of Gen-1 Biotech Inc and Lt. Clea Thorson's boss. Due to the frosty relationship between the two which culminated in Stillwell firing Thorson, NCIS suspected that Stillwell was responsible for Thorson's death after the Lt. died after being struck by a bus. Unfortunately, just as NCIS Special Agents Leroy Jethro Gibbs and Anthony DiNozzo attempted to arrest Stillwell, they got a shock when Stillwell stumbled from his car, begging them to help him but in that moment, Stillwell succumbed to the poison, dying as Gibbs and DiNozzo looked on.