Noah Keller was the former boyfriend of deceased celebrity, Taylor Shane who had a drug problem. He presumably got into a fight with Tom Crawley over Keller's relationship with Taylor before passing out due to the fact that Keller himself had been drinking. As such, Crawley used the opportunity to inject Keller with heroin, eventually resulting in Keller's death with NCIS Special Agents Leroy Jethro Gibbs and Timothy McGee later finding Keller's body in his hotel room a few hours later.