Navy Yard Gunman Told Police He Was Hearing Voices A month before he went on the rampage that left 13 dead, 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 Aug. 7 report from Newport, R.I., police, 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, a 34-year-old information technology employee at a defense-related computer company, used a valid pass Monday to get into the Navy Yard and 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. U.S. 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 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 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. In addition, the House and Senate Veterans' Affairs Committees asked the VA for details about any treatment provided to Alexis. At the U.S. Navy Memorial, in church and on the baseball field, the nation's capital paused to mourn the victims. Hagel laid a wreath at the memorial's "Lone Sailor" statue as taps played. Just a few blocks from the Navy Yard, the Washington Nationals were back to playing baseball after their Monday night game with the Atlanta Braves was postponed because of the shooting. The Nationals wore blue and gold Navy caps during warm-ups, and a moment of silence was held before the first pitch. Those killed included: Michael Arnold, 59, a Navy veteran and avid pilot who was building a light airplane at home; Sylvia Frasier, 53, who worked in computer security; Frank Kohler, 50, a former Rotary Club president in Lexington Park, Md., who proudly reigned as "King Oyster" at the annual seafood festival; and marine engineer and naval architect Vishnu Pandit, 61, an Indian immigrant who preferred the nickname Kisan, Hindi for "peasant." In the Newport, R.I., 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.