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."
According to CBS News, in the past Alexis sought professional help from the VA for his psychological problems.
Newport News mental health expert and veteran, Char Cate, says it’s obvious Alexis fell through the cracks.
"Either he got disgusted with what his help was or they weren't adequately treating his symptoms,” Cate says. “I mean, there's any number of things that could have gone wrong."
Cate served in the Air Force during the Vietnam era. She started a program with area VA hospitals to teach families of veterans about mental health issues.
Cate says even with resources like this, it's still not enough.
"I don't personally feel like all of the VA hospitals are adequately equipped to deal with all of it,” she says. “There are just too many veterans coming out now. It's not like it was in the Vietnam War."
Even though Alexis told police in the past he suffered from PTSD, he was never declared mentally incompetent by the Navy. Despite being arrested on two gun violations, Alexis was issued a security clearance and honorably discharged in 2011.
"I just think when I heard about the firearms issues in the past that to me would have been a red flag, on top of the PTSD," Cate says.
Cate says unless new mental health reforms are put in place, tragedies like Monday’s attack will happen again.
"People need to wake up and smell the coffee and realize that this is not going away," she says.
CNN contributed to this report.