An associate of the Boston-based H Block gang has pleaded guilty to charges related to drug conspiracy in federal court. Mark Linnehan, 26, from West Roxbury, admitted guilt to conspiracy to distribute and possess with intent to distribute controlled substances. Sentencing is scheduled for April 7, 2026, before U.S. District Court Judge Leo T. Sorokin.
Linnehan was among ten H Block members and associates charged in August 2024 after a multi-year investigation that began in 2021. Authorities launched the investigation following an increase in gang-related drug trafficking and violence in Boston. During the probe, law enforcement seized over 500 grams of cocaine, crack cocaine, fentanyl, and more than 20,000 doses of drug-laced paper.
Since the start of the investigation, officials have attributed twelve incidents of gunfire to conflicts involving H Block associates. Six individuals were arrested on drug dealing charges in Boston and nearby areas; four others were already in state custody at the time of arrest. Additional drugs and four firearms were recovered during these operations.
Court documents indicate that between 2022 and 2023, Linnehan participated as a supplier of fentanyl within a broader conspiracy to distribute controlled substances. He also engaged in multiple drug transactions with an undercover officer.
The H Block Street Gang originated as the Humboldt Raiders in Roxbury during the 1980s and re-emerged as H Block in the 2000s. The group is described as one of Boston’s most influential gangs with a history of violent encounters with law enforcement, including a 2015 incident where a member shot a police officer without warning.
If convicted on the charge of conspiracy to distribute and possess with intent to distribute controlled substances, Linnehan faces up to twenty years in prison, supervised release ranging from three years up to life, and fines reaching $1 million. Sentences are determined by federal judges based on U.S. Sentencing Guidelines.
Linnehan is now the ninth defendant to plead guilty in this case.
“United States Attorney Leah B. Foley; Jarod A. Forget, Special Agent in Charge of the Drug Enforcement Administration, New England Field Division; Randy Maloney, Special Agent in Charge of the U.S. Secret Service, Boston Field Office; Ted E., Docks, Special Agent in Charge of the Federal Bureau of Investigation, Boston Division; Boston Police Commissioner Michael Cox; and Russell W. Cunningham Special Agent in Charge of the Department of Justice Office of the Inspector General Mid-Atlantic Region made the announcement.”
The investigation received support from several agencies including Massachusetts State Police; Suffolk County District Attorney’s Office; Massachusetts Department of Corrections; as well as local police departments from Braintree, Quincy, Randolph, and Watertown.
Assistant United States Attorney John T. Dawley from the Organized Crime & Gang Unit and Jeremy Franker from the Justice Department’s Violent Crime & Racketeering Section are prosecuting these cases.
The case falls under the Organized Crime Drug Enforcement Task Forces (OCDETF), which uses coordinated efforts among various agencies to identify and dismantle high-level criminal organizations threatening communities across America through intelligence-driven strategies (https://www.justice.gov/OCDETF).
Authorities remind that details contained within charging documents remain allegations until proven beyond reasonable doubt for any remaining defendants.