HOUSTON --A Harris County judge Wednesday found John Shank not guilty of murdering his mother by reason of insanity. Police said Shank killed his mother, Nancy Shank, in her River Oaks home in December by slashing her throat. Lawyers for both sides presented the judge with evidence that experts found him to be insane at the time of the killing and the judge ruled that he was not guilty by reason of insanity. Shank will go to Vernon State Hospital for 90 days, then to another state hospital. He will undergo re-evaluation each year to see if he is mentally fit for release.