Brown U. janitor says he warned campus security about suspicious visitor twice in weeks leading up to mass shooting

David Propper / NEW YORK POST

A Brown University custodian spotted depraved gunman Claudio Neves Valente pacing school hallways and peering into classrooms nearly a dozen times in the weeks before his mass shooting — and alerted campus security twice about the suspicious figure, a new report said.

Derek Lisi, who has worked at the elite school for 15 years, told the Boston Globe he “knew something was off with” the mass shooter before the sicko opened fire in a lecture hall, killing two students, Dec. 13.

While Lisi said he twice told the same security guard about a suspicious person lurking around the same building in the days leading up to the horror, it’s unclear if any action was taken by the guard or campus officials.

“He’d been casing that place for weeks,’’ looking into classrooms and “circling the hallways,’’ Lisi told the outlet of Neves Valente.

“I thought it was someone trying to steal something. Every time he saw me, I think he thought I was security, because he would always walk away.’’

“I said, ‘Something’s off with this guy, so I gotta say something,’ ” Lisi said. Read more and see video here.