Kayn was the chief surgeon on the neutral research station XK72.
He agreed to go to the Liberator with his assistant Renor to perform surgery on Olag Gan. After deducing Roj Blake’s identity, he delayed the surgery on Gan so he could alert the Terran Federation of Blake’s whereabouts. Blake forced Kayn to perform the surgery, and teleported him and Renor back to XK72.
The station administrator, Farren, tried to intercede when Kayn ordered that XK72 use it’s armaments to destroy the Liberator, so Kayn murdered him. Kayn was then killed when a plasma bolt from one of the Federation ships missed the Liberator, destroying XK72. (A: Breakdown)