Members of Psi Upsilon weren’t sure what to make of the Jason Voorhees-masked man spotted prowling the fraternity’s premises in the early morning hours numerous times over the course of several weeks.

And that uncertainty turned to concern when one of the members awoke to a noise in the night to find the masked man had gained entrance into the house, supply chain management junior and President of Psi Upsilon Brian Seggebruch said.

Footage of the encounter, caught on the fraternity’s security cameras, shows the infiltrator noticing that someone spotted him, then motioning to his friends to leave before bolting out of the house, Seggebruch said.

“It was very nerve-wracking,” he said. “We were all pretty much on edge since we first saw him on our property.”

After that, members focused on securing the house, keeping the doors locked, the valuables safe and upgrading their security equipment.

Seggebruch said although the horror-movie hockey mask was creepy, members feared mostly for their belongings than their lives.

“We felt threatened that something was going to get stolen or broken or that he was around,” he said. “But we didn’t really think it was that serious — we didn’t think he was going to hurt anybody or do anything that serious.”

The events culminated in a “Scooby Doo”-style ending around 3 a.m. on April 15, several weeks after the break-in.

One of the members was out for a smoke that morning on the back porch when he spotted the masked man prowling their parking lot, Seggebruch said. The member ran back in and rounded up several others, who then chased and cornered the man and called the police. The man revealed his face but not his motive.

The man was unknown to the members of the fraternity, and when police questioned him on scene, the only explanation he offered was that he intended to ring the doorbell and run as a prank, East Lansing police Lt. Steve Gonzalez said.

The man, Casey Walker, had no weapons on him and was arrested for a minor in possession charge, Gonzalez said.

It is unknown whether Walker is a student.

With the scare over, Seggebruch said members of the fraternity have relaxed and let down their guards again.

“Now that it’s over, obviously we’re all very relieved,” he said.

The fraternity is considering filing a personal protection order against the suspect, Seggebruch said.