Washington - A month before he went on the shooting rampage that killed 12 people, Washington Navy Yard gunman Aaron Alexis complained to police in Rhode Island that people were talking to him through the walls and ceilings of his hotel rooms and sending microwave vibrations into his body to deprive him of sleep.
The account, contained in a 7 August report from Newport, Rhode Island, police, adds to the picture that has emerged of an agitated and erratic figure whose behaviour and mental state had repeatedly come to authorities' attention but didn't seem to affect his security clearance.
Alexis also apparently managed to exploit seams in the nation's patchwork of complicated gun laws designed to keep weapons out of the hands of dangerous people. He was able to buy a shotgun in Virginia with out-of-state identification, even though that would have prevented him from buying a handgun.
Alexis, a 34-year-old information technology employee at a defence-related computer company, used a valid pass on Monday to get into the Navy Yard and then killed 12 people before he was slain by police in a shootout that lasted more than a half-hour.
A day after the assault, the motive was still a mystery. US law enforcement officials told The Associated Press that investigators had found no manifesto or other writings suggesting a political or religious motivation.
Alexis, a former Navy reservist, had been undergoing mental health treatment from the Department of Veterans Affairs since August but was not stripped of his security clearance, according to the law enforcement officials, who spoke on condition of anonymity because the criminal investigation was still going on.
He had been suffering from a host of serious mental problems, including paranoia and a sleep disorder, and had been hearing voices in his head, the officials said.
The assault is raising more questions about the adequacy of the background checks done on contract employees who hold security clearances - an issue that came up recently with National Security Agency leaker Edward Snowden.
Navy Secretary Ray Mabus ordered two security reviews Tuesday of how well the Navy protects its bases and how accurately it screens its workers.
Similarly, President Barack Obama has ordered the White House budget office to examine security standards for government contractors and employees across federal agencies.
Mert Miller, associate director of Federal Investigative Services for the Office of Personnel Management, said in a statement that federal budget, personnel and intelligence officials were working to "review the oversight, nature and implementation of security and suitability standards for federal employees and contractors".
In general, he said, background security clearance investigations cover information about an individual's criminal history.
In the Newport, Rhode Island incident, Alexis told police he got into an argument with someone as he was getting on a flight from Virginia to Rhode Island, where he was working as a naval contractor, and he said the person sent three people to follow and harass him.
He said he heard voices talking to him through a wall while at one hotel, so he changed hotels twice, but the voices followed him, according to the report. He said he feared they might harm him.
He also "stated that the individuals are using 'some sort of microwave machine' to send vibrations through the ceiling, penetrating his body so he cannot fall asleep".
Later that day, Newport police alerted the Rhode Island naval station and sent a copy of the police report, Newport police Lieutenant William Fitzgerald said on Tuesday.
A spokesperson for the naval station had no comment on Tuesday.
Mental health law
Alexis came to the Washington area about two weeks later and had been staying at hotels. On Saturday, two days before the attack, he went to a Virginia gun store about 24km from the Navy Yard.
He rented a rifle, bought bullets and took target practice at Sharpshooters Small Arms Range, the store's attorney Michael Slocum said. Alexis then bought a shotgun and 24 shells, according to Slocum. Slocum said Alexis passed a federal background check.
It is illegal for gun dealers to sell handguns to such out-of-state buyers, but the Firearms Owners' Protection Act, passed by Congress in 1986, opened up interstate sales for shotguns and rifles.
Virginia gun laws require only that an out-of-state buyer show valid identification, pass a background check and otherwise abide by state laws in order to buy a shotgun in the state. Alexis was never prosecuted for two misdemeanour charges involving guns.
Federal gun laws bar the mentally ill from legally buying guns from licensed dealers. But the law requires that someone be involuntarily committed to a mental health facility or declared mentally ill by a judge, and that information must be reported to the FBI in order to appear on background checks.
In the wake of the mass shooting at Virginia Tech in 2007, state authorities changed state laws to make it tougher for the mentally ill to buy guns there.
But Alexis was never declared mentally ill by a judge or committed to a hospital.
The FBI said during Monday's attack Alexis was armed with a shotgun. Officials said he also took a handgun from a law officer.
In addition to those killed at the Navy Yard attack, eight people were hurt, including three who were shot and wounded, authorities said. Those three were a police officer and two female civilians. They were all expected to survive.
‘No personal issues’
Alexis had run-ins with the law in 2004 and 2010 in Texas and Seattle after he was accused of firing a gun in anger. He was not prosecuted in either case.
And his bouts of insubordination, disorderly conduct and being absent from work without authorisation prompted the Navy to grant him an early - but honourable - discharge in 2011 after nearly four years as a full-time reservist, authorities said.
"He wasn't a stellar sailor," Navy spokesperson Rear Admiral John Kirby told CNN. "We know that."
But he said the offenses weren't "grievously serious" and the punishments for them are fairly mild. Kirby said there was a proposal to "administratively separate him from the Navy," with less than an honourable discharge, but Alexis volunteered to leave early and received an honourable discharge.
"Looking at his offenses while he was in the Navy, that the offenses while he was in uniform, uh, none of those give you an indication that he was capable of this sort of brutal, vicious violence," Kirby said.
As for Alexis' security clearance, Kirby said he received one around the time he enlisted. "It was good for 10 years. And it was at the secret level. So the security clearance was valid when he left the Navy in 2011. And because he wasn't out of work very long before he took this next job, the security clearance went with him."
Alexis joined the Florida-based IT consulting firm The Experts in September 2012, leaving a few months later to return to school. He came back in June to do part-time work at the Washington Navy Yard as a subcontractor, helping the military update computer systems.
The Experts' CEO, Thomas Hoshko, told The Associated Press that Alexis had "no personal issues," and he confirmed that Alexis had been granted a "secret" clearance by the Defence Security Service five years ago.
Alexis' background check "came back clear," Hoshko said.
Among those killed in the Navy Yard shootings was marine engineer and naval architect Vishnu Pandit, aged 61, an immigrant from India.