A Brown University custodian claims he saw the shooting suspect almost a dozen times in the weeks before the Dec. 13 attack on campus and even alerted a campus security guard.

Derek Lisi told The Boston Globe that he noticed a man pacing the hallways at the Barus and Holley engineering and physics building, looking into classrooms and even at one point ducking behind a bathroom in order to avoid being seen. In total, two were killed and another nine people were injured on Dec. 13. Five victims remain at Rhode Island Hospital in stable condition. 

When police shared pictures of the Brown University shooting suspect, Lisi recognized him, saying, “He’d been casing that place for weeks.”

Lisi told the outlet that he saw a man matching police’s description of the suspect, identified as 48-year-old Claudio Manuel Neves Valente, on about 10 occasions dating back to early January.

EVIDENCE SHOWS DEADLY BROWN, MIT SHOOTINGS MAY BE LINKED, SOURCES SAY: REPORT

“I knew there was something off with him,” Lisi said.

In mid-November, Lisi told a security guard at Brown University that he saw the man “circling the hallways.” He said the man was consistently hanging around and peeking into room 166 at the building, where the eventual shooting took place. 

Ella Cook and Mukhammad Aziz Umurzokov were both killed in the shooting. Cook, 19, served as the vice president of the Brown University College Republicans.

WHO IS CHRISTINA PAXSON? THE BROWN UNIVERSITY PRESIDENT FACING INCREASED SCRUTINY OVER MASS SHOOTING RESPONSE

Cook was laid to rest in Birmingham, Alabama, on Monday morning.

Brown University has also retained former U.S. Attorney for Rhode Island Zachary Cunha as it prepares for possible lawsuits.

“Brown works routinely with outside counsel whose expertise complements that of the University’s Office of the General Counsel. In this case, we retained Zachary Cunha, the former United States Attorney for the District of Rhode Island, to assist the University in coordinating with federal, state and local law enforcement agencies,” a Brown spokesperson said.

“I said, ‘Something’s off with this guy, so I gotta say something,’” Lisi recalled thinking when he saw the man on Dec. 1 before going on vacation. “I told my friend, ‘I hope it’s not the guy I’ve been seeing. I hope it’s not.'”

CLICK HERE TO DOWNLOAD THE FOX NEWS APP

Lisi said he spoke with Providence Police on Dec. 15.

The custodian claimed that the Barus and Holley engineering and physics building has been “a free-for-all for a long time.”

“Anybody could just come in,” he added.

Fox News Digital reached out to Brown University for comment.

Fox News’ Brooke Taylor contributed to this report.