Katherine Tate is charged with hindering apprehension or prosecution of a known felon. Conviction is punishable by up to 10 years in prison.
Larry Tate testified Monday that it was a "spontaneous spur of the moment" decision when she reported him missing on Sept. 22, 2008, while swimming off Port Aransas.
Prosecutor Catherine Chopin says Katherine Tate knew her brother was alive as he faced incest charges.