( CNN ) -- Navy Yard gunman Aaron Alexis left a trail of so-called red flags that , in hindsight , seem quite glaring , even if the impetus for this week 's deadly rampage remains murky . For almost 10 years , he showed that he was troubled -- and had a predilection for violence -- even if friends and family members familiar with his emotional problems seem floored that he was disturbed enough to shoot and kill 12 people in Washington on Monday . They may seem like minor episodes when compared with Monday 's shootings , but when pieced together , they provide ample fodder for critics who question how Alexis maintained the security clearance that gave him access to the Navy Yard . 2004 'blackout ' On the morning of May 6 , 2004 , Alexis fired his Glock into two tires of a Honda Accord near a Seattle home where he was staying . He was arrested and charged with malicious mischief . Alexis told police the car 's owner , a construction worker , had disrespected him , leading to an anger-fueled `` blackout , '' according to a police report . His father told Seattle police that Alexis had post-traumatic stress disorder after working as `` an active participant in rescue attempts '' after the 9/11 attacks , the report said . Alexis ' dad further told police his son had anger management issues related to PTSD . `` It appears as if investigators were aware of the incident , interviewed him and were satisfied that it did not preclude granting the clearance , '' a senior naval officer said of Alexis ' 2007 enlistment . Navy chief defends program that screens contractors after audit shows problems . 2008 nightclub arrest . About five months after being granted a `` secret '' security clearance -- the year after joining the Navy -- Alexis was kicked out of a metro Atlanta club for damaging the furnishings , according to a police report . Outside , Alexis cursed profusely , and when he defied police orders to stop , they arrested him for disorderly conduct , the report said . The arrest was integral in the Navy 's decision to try to end his military career , which would n't culminate for another three years , but Alexis was never stripped of his security clearance . 2010 gunfire incident . Fort Worth , Texas , police arrested Alexis in September 2010 after he allegedly fired a bullet through his ceiling into a neighbor 's apartment . According to records , he told police he accidentally fired the weapon while cleaning it . He was calm when police arrived . He was never charged . Texas was Alexis ' last official address , and friend Kristi Suthamtewakul said he spoke Thai , practiced meditation at a Buddhist temple and participated in his community . But he also hinted at a residual anger . `` One of the things he talked about was 9/11 and how he was there and he saw the towers come down from where he was working , '' Suthamtewakul said . `` He had an anger towards the terrorists who did that and took innocent people . '' 2011 Navy discharge . When the Navy began pursuing Alexis ' general discharge , a dismissal that could have affected his security clearance , he had eight instances of misconduct on his record . Among them were insubordination , disorderly conduct , drunkenness and unauthorized absences from work , a U.S. defense official said . He eventually left the service with a less-severe honorable discharge because there were no convictions or evidence to necessitate a general discharge , the official said . Alexis was allowed to keep his security clearance so long as he used it in another official capacity within two years , which he did after gaining employment in September 2012 with a contractor , refreshing computer systems in Japan . In recent weeks , he sought help from a Veterans Affairs hospital in Rhode Island , his second such visit to a VA facility . While authorities are investigating the circumstances of those visits , sources differ on why Alexis wanted help , variously saying he was either hearing voices or having trouble sleeping . Suthamtewakul recalled Alexis expressing impatience with the VA : `` He was very frustrated with the government and how as a veteran he did n't feel like he was getting treated right or fairly . '' Vetting military contractors : How did Navy Yard gunman get in ? August 'microwave machine ' allegation . Last month , police in Newport , Rhode Island , responded to a harassment complaint at a Marriott hotel . There , Alexis told them that someone `` had sent three people to follow him and to talk , keep him awake and send vibrations into his body , '' a police report said . These individuals had followed him to three hotels in the area , Alexis told police , and spoke to him through the walls and floor and used `` some sort of microwave machine '' that sent `` vibrations through the ceiling , penetrating his body so he can not fall asleep , '' according to the August 7 report . Alexis also told authorities , according to the report , that `` he does not have a history of mental illness in his family and that he never had any sort of mental episode . '' Police notified Navy officials , the report said . Asked for comment , Naval Station Newport officials referred CNN to the FBI , which had no comment . CNN 's Mariano Castillo , Chelsea J. Carter and Jake Tapper contributed to this report .
Numerous incidents in Aaron Alexis ' past show that he was troubled , prone to violence . Alexis shooting out the tires of car in Seattle in 2004 is the first in a string of instances . 2010 brings another arrest after Alexis fires a bullet through the ceiling of an apartment . Last month , two years after his Navy discharge , he tells police he heard voices in three hotels .