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 an August 7 police report from Newport, Rhode Island, adds to the picture that has emerged of an agitated and erratic figure whose behavior and mental state had repeatedly come to authorities' attention but didn't seem to affect his security clearance.
Alexis 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 half an hour.
The motive was still a mystery a day after the assault. 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 through the Department of Veterans Affairs since August but was not stripped of his security clearance, according to law enforcement officials, who spoke on condition of anonymity as the criminal investigation is ongoing.
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 on Tuesday of how well the navy protects its bases and how accurately it screens its workers.
Similarly, US 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 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 incident in Newport, 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 that 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 feared they might harm him.
Alexis "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. Alexis came to the Washington area about two weeks later and had been staying at hotels.
He went to a Virginia gun store about 24km from the navy yard on Saturday, two days before the attack, where he rented a rifle and bought bullets before going to Sharpshooters Small Arms Range for target practice, the store's attorney Michael Slocum said.
Alexis then bought a shotgun and 24 shells, according to Slocum. The lawyer said Alexis passed a federal background check.
It is illegal for gun dealers to sell handguns to 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 to buy a shotgun in the state.
Alexis was never prosecuted for two misdemeanor 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 for it 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 Alexis was armed with a shotgun during Monday's attack. And officials said he took a handgun from a law officer during the shooting.
Eight people were hurt in addition to those killed at the navy yard, including three who were shot and wounded, authorities said. Those three were a police officer and two female civilians. They are all expected to survive.
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 honorable – 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 the offences 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 offences while he was in the navy … the offences while he was in uniform … none of those give you an indication that he was capable of this sort of brutal, vicious violence," Kirby said.
As for Alexis's 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 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 chief executive Thomas Hoshko said Alexis had "no personal issues" and confirmed that Alexis had been granted a "secret" clearance by the defence security service five years earlier.
Alexis's background check "came back clear", Hoshko said.
Among those killed in the navy yard shootings was marine engineer and naval architect Vishnu Pandit (61). – Sapa-AP