At some point after the Brood War, Henderson was serving aboard a space platform; one which was unfortunately singled out by the Queen of Blades Along with the rest of his team, Henderson was imprisoned in a cell for unknown reasons.
After six days, the reason for his captivity became clear, an infested terran being sent to retrieve him. Despite a brief struggle and even pleading, Henderson was subject to the formula that Kerrigan was using. Due to incompatibilities between his DNA and the formula the Queen of Blades was using, he emerged from the process as nothing more than a "slobbering, insensate monstrosity."
Neilson, Micky. "StarCraft: Hybrid." Amazing Stories 601 (Spring 2000): 70-75.