Another prosecutor who was set to try two of the remaining officers charged in the arrest and death of Freddie Gray has left the Baltimore state's attorney's office.

The departure of Sarah David follows that of veteran Assistant State's Attorney Lisa Phelps, who quit last week, two days after State's Attorney Marilyn J. Mosby dropped the three pending cases. Sources close to Phelps said she had objected weeks earlier to trying the case of Officer Garrett Miller, which was to have begun July 27.

David confirmed that she had resigned from the state's attorney's office and said she will be joining state Sen. Bobby Zirkin, a Democrat from Baltimore County, as his chief of staff.

David, who joined the office in 2014 and was a prosecutor in the misdemeanor unit, declined to address her reasons for leaving but said they were the same as those reported as the circumstances behind Phelps' departure.

Mosby said she decided to drop the charges because the judge overseeing the trials was unlikely to convict the officers, and she attacked police detectives, whom she accused of undermining the case.

While remarking on the judge and police, Mosby and her top deputies have presented a united front. Neither Phelps nor David appeared at Mosby's news conference and were not mentioned in her remarks. Chief Deputy State's Attorney Michael Schatzow, who tried the first four cases, also played down any friction last week.

“Everybody has moments where they question the witness, they question the legal theory, question something else. For us to start talking about work product conversations — it's not how we run this office,” Schatzow said about reports of Phelps' opposition to the Miller case.

The office has declined to comment on the departures but moved swiftly to replace Phelps, appointing 33-year veteran Sharon Holback to take her place as head of the training division.

In dropping the cases, Mosby said that the criminal justice system is in need of reform and that she would pursue changes to give prosecutors a say in whether defendants can choose a bench trial.

Zirkin, David's new boss and chairman of the Maryland Senate's Judicial Proceedings Committee, has criticized Mosby's comments on the right to bench trials. Zirkin told The Baltimore Sun last week that the idea of giving prosecutors a say in whether bench trials should be granted was “moronic” and had “0.0 chance” of advancing in the legislature.

Zirkin said he had an opening on his staff and has known David for years. She helped manage his first campaign for Senate, and her father was his academic adviser at the Johns Hopkins University.

“I think Sarah is brilliant, and I'm really lucky to have her,” he said.

Phelps and David were chosen in May to prosecute Miller as well as Officer William Porter. Miller, one of the officers who arrested Gray after chasing him near Gilmor Homes, was charged with second-degree assault, reckless endangerment and misconduct in office.

Both Miller and Porter had been compelled to testify under immunity at the trials of their fellow officers, and the new prosecutors were brought in as a “clean team” to ensure that the officers' compelled testimony was not considered at their own trials. The unusual arrangement was designed to preserve the right of the officers to not incriminate themselves.

The charges against Miller and Porter, as well as against Sgt. Alicia White, were dropped July 27 before a hearing at which the state's attorney's office would have been required to show Circuit Judge Barry G. Williams that the “clean team” had not been exposed to any compelled testimony.

Miller's defense attorneys said they expected to raise questions about communication between the original prosecutors and the clean team. Schatzow told reporters last week that prosecutors would have had no problem with scrutiny.

jfenton@baltsun.com