 Whetsel's behavior became erratic in 1938, and after an incident where he "went haywire" during a gig at Rutgers University, he was replaced by trumpeter Wallace Jones.Diagnosed with an inoperable brain tumor, he was confined to the Central Islip State Hospital (later the Central Islip Psychiatric Center) in Suffolk County, New York where he died in May 1940.He is buried in Woodlawn Cemetery in the Bronx, New York.