A New Hampshire man pleaded guilty Wednesday to participating in a bomb hoax that caused a partial evacuation at Harvard University last year.

William A. Giordani, 55, of Manchester, N.H., pleaded guilty in federal court in Boston to one count of concealing a federal felony, a charge which carries up to three years in prison. U.S. District Court Judge Angel Kelley scheduled sentencing for April 25.

According to a law enforcement affidavit filed in his case, Giordani found a post on Craigslist advertising a simple task for $300. All he had to do, according to the ad allegedly written in broken English by a “Nguyen Mihn” asking that the job taker buy some supplies and drop them off to the person’s son at Harvard.

Unfortunately for Giordani, the ad was a ruse. He was to pick up supplies and drop them off as a part of a “proof” that the ad-lister had three bombs placed around Harvard’s campus on April 13, 2023.

A call threatening to detonate the bombs unless the school negotiated a payment of some amount of Bitcoin within 100 minutes of the message declared that the bombs “each have an explosive yield of at least 80 megajoules and contain several pounds of shrapnel,” according to a transcription of the call — which was made via synthesized voice — included in the affidavit. The detonation would be devastating, with the caller estimating “at least 40 students would die and hundreds badly wounded.”

“Make no mistake time is not on your side any attempts to stall or distract us will only subtract from the time you have left to defuse this situation. You have roughly 97 minutes to satisfy our demands less the events of today become a blood and stain on your nation’s history and on the history of Harvard University,” the caller stated.

The call directed police to one of the alleged bombs, to prove the threat was real, placed at the university’s Science Center Plaza. The police evacuated the area and “executed a controlled destruction” of the “bomb.” Inside the red and black Husky-brand cloth tool bag was a package of wire and a small metal safe, with some fireworks inside — which look like just bottle rockets in a photo included in the affidavit. On the wire was a sticker with receipt details that directed investigators to the South Bay Home Depot.

Security camera footage at the South Bay Home Depot would show Giordani picking up supplies, which were bought and paid for online earlier that morning, at 11:45 a.m. the day of the hoax. Other footage would show him placing the bag and its contents at the Science Center Plaza at 2 p.m.

Giordani later told investigators that when he drove to Worcester to collect his fee, the person told him that he couldn’t meet him, wasn’t actually Asian, had no kids and started “spouting off a bunch of racist things about blacks and Jews.”

The U.S. Attorney’s office said in a statement Wednesday that “Once Giordani knew he had been recruited to assist in an extortionate bomb scheme, he had an obligation under federal law to report that scheme to law enforcement authorities. Instead, he deleted incriminating text messages, told his girlfriend not to speak to anyone about it and went on the run from police.”