KEENE, N.H. (MyKeeneNow) An 80-year-old Massachusetts man with ties to a Keene motorsports business has admitted in federal court that he illegally possessed a firearm while working at the shop and interfered with a federal investigation into gun trafficking.

Doug Mulligan pleaded guilty this week in U.S. District Court in Concord to one count of being a prohibited person in possession of a firearm, according to the U.S. Attorney’s Office for New Hampshire. Mulligan, who previously had a felony conviction, was barred under federal law from handling or owning firearms. He is scheduled to be sentenced July 7, 2026, by Judge Joseph N. Laplante.

Authorities say Mulligan had been employed at American Trikes & Motorsports, a federally licensed firearms dealer located on Winchester Street in Keene. While working there, investigators allege he not only handled firearms despite the prohibition but also tipped off individuals who were under federal scrutiny.

According to court filings, Mulligan left a handwritten note on a suspect’s vehicle warning that “ATF is watching u,” alerting them to an ongoing investigation. Federal officials say that action disrupted efforts to track a larger firearms trafficking network.

The case is tied to a broader investigation led by the Bureau of Alcohol, Tobacco, Firearms and Explosives and Homeland Security Investigations into weapons being illegally moved from New Hampshire into Canada. Law enforcement agencies in both the United States and Canada, including the Sûreté du Québec and Ontario Provincial Police, were involved in uncovering the operation, which allegedly smuggled dozens of guns across the border.

Investigators later executed a search warrant and reviewed surveillance footage, which they say showed Mulligan handling and purchasing a firearm on behalf of the Keene business—conduct that violated federal law due to his prior conviction.

Federal prosecutors said the case highlights the importance of enforcing restrictions on who can access firearms and maintaining the integrity of licensed gun dealers. Law enforcement officials also emphasized that interfering with active investigations can pose broader public safety risks.

Mulligan now faces up to 15 years in prison, along with potential fines and supervised release, though any sentence will ultimately be determined by the court under federal guidelines.

The Keene Police Department assisted in the investigation alongside federal authorities.