Mitchell Stewart was a Ukranian developer and seller of the Cordilla Virus during Day 3. He was infected with the virus when his employer, Johnathan Samuels, wanted him to plant a vial of the virus in the Comfort Inn and Suites Hotel. He died at around 12:30am.
During Day 3, Rick Jackson contacted Stewart with the Hernandez brothers to go buy the virus. When they got there, Stewart stated that there was another buyer intrested in the virus, Abdul Amad. Abdul later won the silent auction and Stewart gave him the virus. After Sergio Hernandez stole the virus from Abdul, it exploded, revealing Mitchell Stewart had given the buyer a decoy so he could escape with the money and real virus.
Later, he met with Johnathan Samuels, his real buyer. Samuels said he wouldn't pay all the money for the virus unless Stewart delivered a vial to the Comfort Inn and Suites Hotel. Stewart claimed he was a business man, not a henchman, but Sameuls persisted. Once Stewart got there, Samuels told Stewart via headset that he couldn't afford for Stewart to tell the authorities about him if Stewart got caught. Samuels then also mentioned about the memory defects that the virus enflicts, before releasing it remotly, and infecting Stewart. When Jake Andrews arrived at the hotel, Stewart was already showing symptoms of the virus. It was revealed later in a split screen that Stewart was dead.