A Boston man, James Thelwell-Mullen, appeared in federal court today where he pleaded guilty to the unlawful possession of a machinegun. U.S. District Court Judge Allison D. Burroughs presided over the plea, with sentencing set for July 29, 2025. Thelwell-Mullen, aged 32, was indicted by a federal grand jury in July 2024.
On or around April 28, 2023, Thelwell-Mullen was found to have a machinegun conversion device, known as a "Glock switch", aimed at enabling a Glock semi-automatic pistol to automatically fire. Court records show that a search of his Boston home led to the discovery of this device, two homemade guns, ammunition, firearm magazines, various gun accessories, as well as a bag of fentanyl. Messages on Thelwell-Mullen's phone suggested he was involved in the sale of machinegun conversion devices.
The statutory provision for this offense includes potential penalties of up to 10 years in prison, a supervised release period of three years, and a fine up to $250,000. Federal district court judges determine sentences based on the U.S. Sentencing Guidelines and other statutory factors.
The announcement was made by United States Attorney Leah B. Foley, alongside officials James M. Ferguson, Special Agent in Charge of the Bureau of Alcohol, Tobacco, Firearms and Explosives in the Boston Field Division, and Boston Police Commissioner Michael Cox. Assistant U.S. Attorney Elianna J. Nuzum from the Criminal Division is handling the prosecution.