Ex-Braintree detective charged with criminal harassment over alleged Flock, GPS misuse

Event: September 18, 2026 · First reported: September 19, 2026 · 3 sources

Mark Sherrick, 55, a retired Braintree, Massachusetts police detective, faces a misdemeanor criminal harassment charge over allegations he used department resources — including Flock license plate readers, a department phone, tablet and cruiser, and a GPS tracker — to monitor an ex-girlfriend after their 2024 breakup. Braintree officials said a third-party investigation found he misused police resources, including license plate queries, for a personal matter with no legitimate investigative purpose; he retired in April 2025 while that inquiry was underway. Boston 25 News reported he queried his ex's plate in the Flock system more than 1,000 times. The allegations have not been tested in court; arraignment was scheduled for Sept. 29.

Why this matters

The case is one of several in Massachusetts in which officers are alleged to have used automated license plate reader systems for personal surveillance, raising questions about what auditing and access controls exist before misuse is detected.

Key facts

Sherrick, 55, retired in April 2025 during an official investigation and is charged with one misdemeanor count of criminal harassment.
Braintree said a third-party investigation found he misused police resources, including license plate queries, for a personal matter.
Court documents allege he received GPS tracking alerts at his department email that matched the woman's movements; Boston 25 News reported more than 1,000 Flock queries of her plate.
State POST Commission records list sustained allegations including an improper query of a town employee and placing a GPS device on a vehicle; his certification is listed as 'restricted.'
Stow, New Bedford and Lynn police departments have separately suspended Flock use or placed officers on leave amid similar allegations.

Timeline

September 19, 2026Former Braintree detective charged with allegedly using Flock, other police tools to harass his ex
September 29, 2026Former Mass. detective accused of using Flock cameras to harass ex-girlfriend due in court
October 16, 2026Former Braintree detective accused of using Flock cameras to track ex-girlfriend due in court

Sources

This summary was written from the published reporting below and links to it; BlockFlockNow does not reproduce article text.

Former Braintree detective charged with allegedly using Flock, other police tools to harass his ex (Boston.com, September 19, 2026)
Former Mass. detective accused of using Flock cameras to harass ex-girlfriend due in court (Wcvb, September 29, 2026)
Former Braintree detective accused of using Flock cameras to track ex-girlfriend due in court (Boston 25 News, October 16, 2026)

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About this record

BlockFlockNow documents reported incidents involving Flock Safety cameras and automated license plate readers: council votes, contract decisions, misuse by authorized users, lawsuits, audits, and community response. Every record is reviewed by a person before publication. New to the topic? Start with What is Flock?, find meetings near you, or learn how to request your town's camera records.

Updated October 16, 2026. Corrections: blockflock@bytebunny.io. See all documented incidents or search the full article archive.