Numbuh 19 was a guard in the Deep Sea Research Facility, where he guarded the vehicle storage area.
19, like most operatives, was trained at the KND Arctic Academy and Prison. 19 was first to be stationed at Sector F, but he was transferred to the Research Facility shortly before going to Sector F.
Later, Numbuh 19 was in a battle within the facility when it was invaded by Teen Ninjas. Soon after, a sickness was released and infected the Teen attack group. Numbuh 19 guarded the door to where the escape pods were, and being the last one to leave, but before he reached the pods, he was infected by a teen. But in the seconds he turned to a zombie, he shut the door closed and it locked from the inside the pod room, giving more time for the survivors to escape.
Some operatives later claimed seeing 19 as a zombie when the Facility was taken back. His status after that is unknown.