It is known that in 1993 John joined the U.S. Army to avoid a jail sentence , where he served as an Infantryman , Ranger and Special Forces soldier with the 1st Special Forces Group , before discharged as a Sergeant First Class after 12 years of service . While he was stationed at Fort Lewis , Washington in 2001 , John met Jessica Arndt , a nurse with whom he fell in love . On a vacation to Mexico , he tells Jessica that he has left the Army just as Jessica witnesses the Twin Towers fall on television , and they both realize his career is far from over . Eventually , John breaks up with Jessica , and is recruited by the CIA . Some time after that , they meet by chance in an airport , where a newly engaged Jessica gives John a final opportunity to save their relationship by asking her to wait for him ; he is unable to do so
Twin Towers fall
September 11 attacks
John Reese (Person of Interest)