The leader of a group opposing Boston's COVID-19 vaccine mandate for first responders has been placed on administrative leave while an internal affairs investigation proceeds. A Boston Police Department spokesperson confirmed on Monday that Sgt. Shana Cottone, who heads Boston First Responders United, is off duty from the department.

The Boston Herald first reported the development on Sunday, saying Cottone is the subject of an open internal affairs probe and that no additional details were available. Cottone told the newspaper that officers came to her home on Saturday and took her gun and badge.

"They're trying to come after me, to silence me," Cottone told the outlet. "They're not going to silence me."

On Sunday, Boston First Responders United shared a link to the Herald story on Twitter. The group's post said that when dissident voices are silenced, "the PEOPLE must raise their voices louder, stronger and TOGETHER!" It also included a line beginning, "To learn who rules over you, simply find out who you are not allowed to criticize." That saying is often wrongly credited to the 18th-century French philosopher Voltaire. According to the Associated Press, it is actually a reworking of remarks by Kevin Alfred Strom, an American white nationalist and Holocaust denier.

The group is challenging a mandate from Mayor Michelle Wu requiring city employees to receive a dose of the vaccine by Jan. 15, a policy introduced as virus cases surge. The Herald reported that Cottone objects to getting vaccinated for religious reasons.

Boston First Responders United is one of several public-safety organizations, including the Boston Police Superior Officers Federation, that have joined a lawsuit seeking to block the mandate. The Herald reported that a hearing in the case is scheduled for Tuesday.

The federation, which is the union representing Cottone, said it plans to review the decision to put her on leave. In a statement, it described her as "one of the most vocal opponents of the new vaccine mandate." The union added: "While we do not always share the manner, tone or language this individual has used to criticize the policy and City officials, the timing of this action by the City raises questions, as it occurred just a few days before a court hearing to enforce an agreement allowing supervisors to submit to a weekly test [in] lieu of a vaccine."

Last week, Boston First Responders United was among the organizers of a demonstration against the vaccine requirement that drew several hundred people to downtown Boston. According to the Herald, Cottone said at that time that she felt as though she was "planning my own funeral," because she expected to be fired for not being vaccinated.