A tissue sample from the brain of a gunman who killed 18 people and injured 13 others in Maine has been sent to a lab in Massachusetts to be examined for signs of injury or trauma related to his service in the Army Reserves, officials said Monday. The state's chief medical examiner wants to know if a brain injury stemming from 40-year-old Robert Card's military service could have contributed to unusual behavior he exhibited leading up to the Oct. 25 shootings at a bowling alley and at a bar in Lewiston . A spokesperson for the medical examiner's office characterized the extra step as a matter of thoroughness “due to the combined history of military experience and actions.”