A biology teacher in Massachusetts tried to plant live ammunition in a school stairwell on Thursday to scare the school into increasing security. Unfortunately for him, the whole thing was caught by a security camera and he was quickly arrested.

What happened?

Alfred Purcell, 57, was reportedly frustrated that Southbridge High School was not adding metal detectors, so he decided to take matters in his own hands.

On surveillance footage, Purcell can be seen discreetly dropping a 9 mm bullet on the floor in a school stairwell, and then leaving the scene.

Ten minutes later he returned, acting like he was just discovering the bullet for first time. He took a photo of it with his cellphone, and called on his radio for back up.

The school went on lockdown, but police quickly identified the culprit when they played back the surveillance footage from a camera that Purcell seemed not to have noticed.

"There was no kids that were injured, nobody was seriously impacted by this other than we went into a lockdown for an hour and we had to investigate a teacher who was doing things he shouldn't be doing," Southbridge Police Chief Shane Woodson told WCVB-TV.

Woodson said at a news conference that Purcell had admitted to police that he planted the bullet to "prove to the school that they needed to get metal detectors."

What else?

Despite the surveillance footage, his attorney is denying that he had "any contact with the bullet at all."

According to WCVB, Purcell was charged with "two counts of the unlawful possession of ammunition, two counts of carrying ammunition on school grounds, disturbing a school assembly, disorderly conduct and disturbing the peace."

He has also been banned from returning to the school. Even before this incident, the school had decided not to renew his contract.