The former Navy reservist who killed 12 people at the Washington Navy Yard had been hearing voices and was being treated in Rhode Island for mental illness in the weeks before the shooting rampage, CNN reported.
Aaron Alexis, a 34-year-old information technology employee with a defense contractor, used a valid pass to get into the highly secured installation Monday morning and started firing inside a building. He was killed in a gun battle with police.
Newport police said Alexis called them last month to complain that voices were harassing him through the walls of his hotel room and he worried they might harm him.
Police said they were called to a Marriott around 6 a.m. Aug. 7. Alexis told them he was in town as a naval contractor. Newport is home to a naval station.
Police said Alexis said he had had an argument with two black men and a black woman at the airport, and then claimed the three people were still following him. He said he first heard them talking to him through a wall while at the Residence Inn in Middletown.
According to a police report, Alexis packed up and then went to a hotel on the U.S. Navy base where he heard the same voices talking to him through the walls, floor and ceiling.
Alexis told police he then moved to the Marriott where the three people were speaking him through the floor and ceiling. He also said the people were using some sort of microwave machine to send vibrations through the ceiling so he couldn't fall asleep.
Police asked him for better descriptions of the individuals he was worried about, but Alexis did not go any further.
Alexis told police he was fine emotionally and physically and said he did not need any further assistance from them but remained concerned about the people from the airport.
Police ran a background check and no warrants or any other information came back on Alexis so they left after responding to his call.
Lt. William Fitzgerald of the Newport Police Department says police alerted security at the naval station. A spokeswoman for the station referred calls to the FBI.
CNN reported that Alexis tried to get help at a Veterans Affairs facility in Rhode Island.
The motive for the mass shooting in Washington - the deadliest on a military installation in the U.S. since the attack at Fort Hood, Texas, in 2009 - was a mystery, investigators said.
CNN and the Associated Press contributed to this report.