When Kirk orders McCoy's commission reactivated in ' (1979); a resentful McCoy complains of being "drafted". Spock transfers his "katra"—his knowledge and experience—into McCoy before dying in ' (1982). This causes mental anguish for McCoy, who in ' (1984) helps restore Spock's katra to his reanimated body. McCoy continues to serve on Kirk's crew aboard the captured Klingon ship in ' (1986). In "" (1989), McCoy (through the intervention of Spock's half-brother Sybok) reveals that he helped his father commit suicide to relieve him of his pain. Shortly after the suicide, a cure was found for his father's disease, and McCoy had carried the guilt about it with him until Sybok's intervention.