BALTIMORE (WJZ) — A lawyer for the Baltimore Police Department sergeant who ran a corrupt gun unit says his client will not turn against fellow officers as a government witness.

Thomas Allers’ lawyer says his client will not testify against fellow officers as part of his guilty plea to federal charges related to a corrupt gun unit.

READ MORE: 'The School Shouldn't Be Open Right Now': Parents React To COVID-19 Outbreak At Cherry Hill Elementary Middle School

Lawyer Gary Proctor said Allers “will plead guilty only to what he did,” and has no deal to turn against eight other former officers who were indicted in the Broken Boundaries corruption investigation.

A federal indictment lists Allers as the officer-in-charge of the Gun Trace Task Force, an elite gun crimes unit, from July 2013 until June 2016. Federal prosecutors allege he tipped off other officers that they were under investigation.

Baltimore City State’s Attorney Marilyn Mosby told WJZ Investigator Mike Hellgren that 277 cases have been impacted by the tainted gun unit, but there could be more “because we’re learning more information daily.”

“We never want to be in a position where you’re confronted with officers who have usurped their authority… some have already pleaded guilty to robbing folks, racketeering, fraud, and because of their actions, people have been killed,” Mosby said. “If there are ways in which we can prove these cases without that officer, whose credibility has clearly been called into question, then we’re going to do so.”

READ MORE: Almost 9,000 Vaccinated Marylanders Get Additional Shots Since Approval of Pfizer Booster

The corrupt gun unit has a connection to murdered detective Sean Suiter, who was scheduled to testify before a grand jury as part of the investigation the day after his killing. Commissioner Kevin Davis has said there’s no evidence that is the reason Suiter was shot. He has asked the FBI to take over the investigation into Suiter’s murder.

Sergeant Allers has been with the BPD since 1996. The 28-page indictment lays out a number of charges, accusing Allers of stealing tens of thousands of dollars from citizens in Baltimore City, Baltimore County, and Anne Arundel County.

In some of the cases, the victims were restrained. Prosecutors said in one case, Allers referred to it as taking “lunch money.”

In an April 2016 robbery and extortion, prosecutors contend Allers arrested a man, then went to his home and stole more than $10,000. That man was later released and killed because he could not pay a drug debt.

“I do worry that the actions of these officers have eroded public trust, but I am also confident that people understand and recognize the actions of a few don’t represent the entirety of the police department,” Mosby said.

MORE NEWS: 'We're The Cure To This Situation': 9 Killed, 13 Wounded In Baltimore Over The Past Week

Follow @CBSBaltimore on Twitter and like WJZ-TV | CBS Baltimore on Facebook