Keith Dillon was a Petty Officer whose murder and eventual disappearance prompted Special Agent Leroy Jethro Gibbs and his team to be called to investigate. Having washed out of SEAL training, Dillon, feeling the need to prove himself created the alias and fictional person, "Robert J. Thorne" while carrying out contract killings. He was later strangled to death by Jeremy Pryor with resident Erin Kendall witnessing his death by pure chance.