BOSTON (AP) — The commander of the Massachusetts State Police who was supposed to reform the department after a series of scandals instead broke rules to promote his allies, while at the same time disenfranchising women, troopers of color, and older troopers, according to a lawsuit filed by three veteran supervisors.

The suit alleges that Col. Christopher Mason’s former driver and chief of staff, who had the best score on a promotion exam, and two other top-scoring troopers coauthored an exam study guide that was “suspiciously predictive” of questions, The Boston Globe reported Wednesday.

The guide is “strong evidence that test takers had access in advance to specific testing questions and answers” and that Mason and the command staff “turned a blind eye” to potential cheating, the suit says.

Following the exam, Mason rushed a promotion process to advance those closest to him — most notably his former driver — before a new state law took hold and changed the process, according to the suit.

Mason declined to be interviewed, but department spokesperson David Procopio denied the suit’s claims. The recent “promotional examination was prepared, announced, administered, and graded fairly, properly, and consistently, and in the same manner as past tests. Accusations of cheating are baseless and we reject them categorically,” he said.

Nevertheless, the agency’s internal affairs unit is reviewing the exam process in the interest of transparency, he said.

Gov. Charlie Baker, who appointed Mason in 2019, declined to comment through a spokesperson.

Among the plaintiffs are a 57-year-old woman and a 61-year-old man who identifies as Black and Hispanic.

The department has had several scandals in recent years that have eroded public trust, including widespread overtime abuse that resulted in criminal charges against several active and retired troopers.