While the Berkshire district attorney determined officers involved in the incident that led to the death of 27-year-old Biagio Kauvil acted lawfully, decisions made by Hinsdale Police Chief Shawn Boyne and Sgt. Dom Crupi – who are both on administrative leave – were identified as being in need of review.
And in April, the neighboring Dalton Police Department, which sent two officers to support Hinsdale during Kauvil’s crisis on Jan. 7, told Hinsdale leaders that it was breaking its mutual aid agreement. In issuing that announcement, Dalton’s police chief cited both the Kauvil killing and past tensions with the Hinsdale PD.
Now, newly obtained records detail conduct by then-Hinsdale Police Officer Mathieu Mercier that’s at the root of that tension.
The details come after a WAMC Freedom of Information Act request uncovered years of formal complaints directed at Hinsdale from Dalton to do with a range of issues, including a threat made by Mercier to a Dalton dispatcher that Dalton Police Chief Deanna Strout described as “graphic” and “would most certainly rise to a level of a criminal investigation” if it had been made by a civilian.
Much of the new detail comes from a Feb. 6, 2024, letter from then-Hinsdale Sgt. Elizabeth Zipp to former Hinsdale Police Chief Susan Rathbun. In it, Zipp describes Mercier as creating a mutual-aid work environment hostile enough for her to feel “tormented.” She described no longer feeling safe to be alone in the same room with him.
Zipp’s letter describes one 2023 interaction in which she says she attempted to address Mercier allegedly ignoring the department’s protocols and chain of command. She wrote that he made a threatening “Trooper knife hand” gesture at her repeatedly and clenched his hand into a fist during their conversation.
Zipp’s letter goes on to explain to Rathbun why she believed Mercier might become violent. According to the then sergeant, Mercier in 2023 allegedly said he wanted a Dalton dispatcher to die and that “he [wanted] to watch her bleed out and [didn’t] care that she has a child.”
In her letter, Zipp also says on the way to a firearms training, Mercier pointed out the college he attended and was arrested at, and that “if she [got] a call that someone shot up the school it was probably him.” Zipp’s letter also says Mercier regularly made references to Hitler in text messages, and that he had a reputation for racism and insubordination at other jobs and police departments.
In a letter dated Feb. 5, 2024 – the day before Zipp’s message to Rathbun – Mercier tells the then-Hinsdale chief that he was preemptively denying any claim that he had raised his voice or disrespected his sergeant, and that he remained seated and at a distance from Zipp during the encounter. He writes that the need for his letter is “utterly stupid” but necessary due to previous allegations made about him by Zipp, and that he felt Rathbun should know about the interactions “so that should she claim that [he] did anything [the chief] would have [his] account of events.”
Months earlier, on Jan. 29, 2024, records show Zipp emailed Rathbun to call for a meeting with Officers Mercier and Jose Gonzalez to handle chain of command and communication issues.
WAMC has previously reported that members of the Dalton PD formally complained about Gonzales’ behavior during a bloody mental health response in April 2025.
Following Zipp's complaints to her superior, Rathbun’s handling of Mercier’s threats toward the Dalton dispatcher was part of a breakdown in the relationship between the police departments.
Zipp resigned from the Hinsdale PD not long after her letter to Rathbun, and now works for the North Adams PD.
Rathbun retired as chief by the middle of 2024.
Mercier also left the Hinsdale PD around that time, and worked in the nearby Cheshire PD until he resigned from that role in January.
According to the May 2026 Massachusetts Peace Officer Standards and Training Commission disciplinary records, Mercier currently has a restricted certification status and is unassociated with any law enforcement agencies in the commonwealth. In May 2024, he had seven official misconduct charges related to his time in the Hinsdale PD, ranging from harassment over threatening statements, insubordination, and neglect of duty to chewing tobacco while on duty, accessing authorized files while suspended, and refusal to follow basic police protocols.
While Hinsdale has contracted a law firm to carry out an investigation into its police department, it chose one with past professional ties to Chief Shawn Boyne.
When asked about Zipp's email concerning Mercier's behavior, Acting Hinsdale Police Chief Bruce Cullett said "it appears that there was significant tension between Sgt. Zipp and Officer Mercier in early 2024."
He also said documents that are part of a pending records request will “shed additional light on those issues” and that corrective steps were taken at the time.
WAMC has reached out to Mercier for comment on this story.
