The FBI is joining the search for 18-year-old Brendan Santo, a Grand Valley State University student who’s been missing since visiting friends in East Lansing the weekend of the Michigan State-Michigan game.

Santo last was seen around midnight Oct. 29 on MSU’s campus near Yakeley Hall, authorities said. He was wearing gray sweatpants, a black T-shirt, a Detroit Red Wings cap and Converse high tops, police said. He’s about 5-foot-10, 160 pounds.

“At this point, foul play is not suspected in Brendan Santo’s disappearance, and we have received no other reports of missing persons,” MSU police said in a statement last week. “We also do not believe that Brendan intended to harm himself.”

“I’ve been talking to a lot of his friends lately, and his friends are just so devastated,” said Dawn Brewer, Santo’s aunt. “They’re really a close-knit group, and they really care about each other, and they’re just hoping that he comes back.”

Police said they’ve searched by foot, helicopter, drone and boat on the Red Cedar River, near Santo’s last known location.

“Red Cedar River is still of particular interest to us based on investigative leads, and will be continued to be searched,” said Chris Rozman, an inspector with MSU Police Department. “Our genuine hope is that with these additional resources and collaboration we will ensure that all investigative avenues are being explored. And the work that we have already done can be reviewed by other professional agencies.”

A family-run Facebook page called “Bring Brendan Santo Home” had more than 5,600 members as of Tuesday. Brewer and hundreds of others have formed search parties to scour the Michigan State campus and surrounding areas in East Lansing.

“We had to have at least over 500 people searching — people that we knew about,” Brewer recalled. “I know other MSU students were out there just searching, you know … they’re like, ‘We know this campus, we know where to look.’ The amount of support we’ve gotten just floors me, that these people have been so amazing and so wonderful to help us find Brendan.”

The Santo family is offering a $5,000 reward to anyone with credible information that leads to finding Brendan. Tips can be shared with MSUPD at 844-99-MSUPD or Crime Stoppers at 517-483-STOP.