Washington (CNN) -- In the early morning hours of August 10, 2008, Aaron Alexis -- now known as the Washington Navy Yard shooter -- was arrested for disorderly conduct in metro Atlanta. The then-Navy reservist was kicked out of a club for damaging the furnishings and left the place releasing an unrelenting string of profanities even as police officers told him to stop.
He kept cussing and he was taken in, according to a police report.
An angry overreaction, maybe, but one that his military superiors noticed.
Was this just one side of an isolated incident? Or was it a warning sign of someone suffering from trauma dating back to the 9/11 attacks? It was this confrontation along with another arrest in Texas that prompted the Navy to begin proceedings to separate him from the military.
By the time the Navy began to seek a "general discharge" for Alexis, he had eight instances of misconduct on his record, including insubordination, disorderly conduct, unauthorized absences from work, and at least one instance of drunkenness. But in the end, he left the service with an honorable discharge because he had never been convicted and there was a lack of evidence to merit a general discharge, a U.S. defense official said.
A general discharge might have hindered his ability to get work in the civilian sector.
As it tragically played out, Alexis was working as a military contractor when he opened fire Monday at the Washington Navy Yard in the District of Columbia.
Authorities have not released their thoughts on Alexis' motive in the morning shooting at the headquarters for Naval Sea Systems Command that left 12 people -- and the gunman -- dead. But a friend said Alexis was locked in a dispute over money with the company that contracted him to work for the Navy.
Investigators also learned that Alexis had recently made contact with two Veterans Affairs hospitals for apparent psychological issues, law enforcement sources told CNN on Tuesday. However, other sources said Alexis sought help from the VA for sleep-related issues.
He told Newport, Rhode Island, police last month that an individual "had sent three people to follow him and to talk, keep him awake and send vibrations into his body," according to a police report.
Authorities said earlier that they are confident that Alexis was the lone gunman, after a daylong police search for a possible second suspect.
Trauma from 9/11?
The September 11, 2001, terrorist attacks were the catalyst that triggered Alexis to leave his home in New York City, according to a source with direct knowledge of the investigation.
He could not deal with the attack, left New York and essentially became a wanderer going from place to place -- San Diego, Texas, and overseas, the source said.
His father told Seattle police in 2004 that his son was suffering from post-traumatic stress disorder after taking part in 9/11 rescue efforts, according to police records.
Alexis has not been back to New York since 2010, the source said. His parents, divorced, both live in Queens, and have been interviewed by authorities.
The source with direct knowledge of the investigation said that, based on family accounts, it appears Alexis "basically snapped."
According to the source, Alexis was "having problems sleeping" and was "hearing voices." He was growing increasingly troubled and in recent months had exhibited signs of mental problems and, the source said, he tried to get help at a VA facility in Rhode Island.
Last month, Alexis told Newport, Rhode Island, police that an individual "had sent three people to follow him and to talk, keep him awake and send vibrations into his body," according to a police report.
According to that report, which is related to an investigation into a harassment complaint at a Marriott hotel in Newport, Alexis said he first heard the people "talking to him through a wall" at a Residence Inn in Middletown, Rhode Island, where he'd been staying.
He packed up and went to an unidentified hotel on a Navy base in Newport where he heard the same voices talking to him. He moved to a third hotel, the Marriott, according to the police report. There, Alexis first told authorities that the three individuals spoke to him through the floor and then the ceiling.
Alexis said the individuals were using "some sort of microwave machine" that sent "vibrations through the ceiling, penetrating his body so he cannot fall asleep." He told authorities, according to the police report, that "he does not have a history of mental illness in his family and that he never had any sort of mental episode."
Newport police said they referred the matter to the Newport naval base. That facility on Tuesday deferred comment to the FBI, which would not speak about the report.
Alexis is believed to have arrived in the Washington area last week, when he checked into a hotel, according to someone who met him at the hotel. The person, who declined to be identified, said Alexis indicated he planned to be in the area for several weeks.
At the time of the shooting, Alexis was working for The Experts, a subcontractor of HP Enterprise Services that was contracted to "refresh equipment used on the Navy Marine Corps Intranet network," according to a statement released by the company.
Alexis, who had Department of Defense security clearance, worked from September 2012 through January refreshing computer systems in Japan, said Thomas E. Hoshko, the CEO of The Experts.
His security clearance was renewed in July to carry out the same type of contract work at the Navy Yard, Hoshko said.
Alexis returned to work with The Experts that same month, he said. He worked at facilities in Rhode Island, North Carolina and Virginia for weeks at a time upgrading computer systems, Hoshko said.
No one reported having any problems with him during those assignments, the chief executive said.
Alexis began working at the Navy Yard last week, though it was unclear whether he had actually begun working or was still securing his base clearance, Hoshko said.
Alexis served as a full-time Navy reservist between 2007 and 2011, according to military records. He achieved the rank of aviation electrician's mate 3rd class, working on aircraft electrical systems, the records show.
From February 2001 until February 2003, he worked for the Borough of Manhattan Community College as a college assistant in the administrative computing office, according to spokesman Barry Rosen.
Barry Williams, who was Alexis' supervisor there, said the suspect become easily frustrated over small things and could hold a grudge, but that he never saw him get violent.
Alexis, who managed switches and networking in the office, was a better than average worker, Williams said.
While the FBI are urging anyone with information about Alexis to come forward, investigators are focusing on reported incidents, including police run-ins, that portray a man with increasingly violent tendencies.
There were no indications that Alexis had any ideological differences with the Navy or any disagreements with anyone at the Navy Yard, according to a U.S. law enforcement official with knowledge of the investigation.
Alexis' family reeled at the news that he is believed to be the man behind the killings.
"What I do know is he wasn't that type of person," Anthony Little, who identified himself as Alexis' brother-in-law, told reporters outside his home in the Brooklyn borough of New York City. "I didn't really hear anything that would make me feel, as a newcomer to the family, that somebody should be watching him."
He said the family's initial reaction was "very distraught, very stressed out, tears."
"You know, they didn't see it coming," said Little, who is married to Alexis' sister Naomi. "Their hearts are going out more to the victims and the people that got hurt because, you know, there's more lives lost and we don't need that right now. We really don't."
Melinda Downs, a friend of Alexis', said she spoke to him a week ago and he gave no indication of what was to come.
"It is like Dr. Jekyll and Mr. Hyde. Who was this guy?" she asked.
Downs described Alexis as intellectual.
"His mind was sound. He could hold conversations with the best of us," she said. "If he did (hear voices), he hid it very well."
She said Alexis had good relationship with his family, but a tough one with his father.
"You ask yourself, you go from denial, to reality, to fear, to blame. Is there something I could have done? ... Is there some type of behavior that I ignored or didn't see. That I could have prevented this. But there is no answers," Downs said.
Alexis appeared to have had sporadic run-ins with the law, dating back to at least 2004, when he was arrested in Seattle, accused of shooting out the tires of a man's truck in an anger-fueled "blackout," according to a Seattle Police Department report.
He told investigators he believed the man, a construction worker, was mocking him, but had no memory of shooting out the tires, the report said.
Investigators later spoke with Alexis' father, who told police that his son had anger management problems associated with post-traumatic stress disorder, which he suffered after working "as an active participant in rescue attempts" during the 9/11 attacks, the report said.
And in 2010, Alexis was arrested by Fort Worth, Texas, police but never charged over an allegation that he fired a gun through the ceiling of his apartment. According to records, he told police he accidentally fired it while cleaning it.
His last known address was outside of Fort Worth, where he was roommates for three years with Nutpisit Suthamtewakul, who described Alexis as his best friend.
Alexis befriended Suthamtewakul four years ago after he emigrated from Thailand.
Alexis taught him about American culture, Suthamtewakul told CNN. Alexis, he said, was fluent in Thai and attended a Buddhist temple.
When Suthamtewakul opened the Happy Bowl Thai Restaurant, Alexis would occasionally help out, waiting tables, he said.
The two were roommates until five months ago, when Suthamtewakul got married and Alexis had to move out.
Toward the end, Alexis spent a lot of time holed up in his room, keeping to himself, Suthamtewakul said.
On Monday, Suthamtewakul was stunned by the news that Alexis was said to be the shooter in the rampage at the Navy Yard.
"I can't believe he did this," he said. "He never showed any sign of violence."
But there were signs that Alexis was unhappy.
He was having a hard time trying to get on his feet, said Suthamtewakul's wife, Kristi. He helped out at the restaurant but not for pay.
"He was using this as an educational experience to help learn Thai," she said. He enjoyed making deliveries to homes, where the language was spoken. He talked about moving to Thailand.
But to Suthamtewakul, Alexis seemed "frustrated with life."
She is grieving. "He was like one of our best friends, like a brother to us and always willing to go out of his way to help us out with things," she said.
He was very frustrated with the company that contracted him to work for the Navy, according to another friend.
Alexis claimed he wasn't paid properly by the company after returning from a months-long assignment to Japan last year, said Michael Ritrovato, another former roommate.
It was unclear whether the dispute was over salary or expenses. Alexis just felt the company owed him money and had not paid him, Ritrovato said.
He is in shock over his friend's actions.
"He was an easygoing guy. I don't know of any reason for this," he said.
But Ritrovato knew Alexis was fascinated by guns. "He was ... knowledgeable with military rifles and handguns. At least he led us to believe he was. But nobody ever had the idea that he would use them in a derogatory way," he said.
Two days before the shooting, Alexis spent "a couple hours" shooting at Sharpshooters Small Arms Range in Northern Virginia before paying $419 for the Remington 870 shotgun -- after being approved by the federal background check -- and a small amount of ammunition, the store's attorney, J. Michael Slocum, said.
It is not clear whether Alexis was still living in Fort Worth area at the time of the shooting.
CNN's Evan Perez reported from Washington and Ed Lavandera reported from Fort Worth. Mariano Castillo and Chelsea J. Carter wrote this report from Atlanta. CNN's Brian Todd, Susan Candiotti, Barbara Starr, Jake Tapper, John King, Pamela Brown, Deborah Feyerick, Alan Silverleib, Dan Merica and Larry Shaugnessy contributed to this report.