A new team of prosecutors has been tapped to try the cases of two officers charged in the arrest and death of Freddie Gray who have been compelled to testify against Officer Edward Nero at his trial that begins this week.

Multiple sources told The Baltimore Sun that a memo was sent out Monday night to prosecutors notifying them that Lisa Phelps, a veteran assistant state's attorney, and Sarah David, who joined the office in 2014, were selected to be part of what is called a “clean team.”

Two officers charged in the case — William G. Porter and Garrett Miller — have been ordered to testify under immunity against their fellow officers, and prosecutors will have to prove that they did not allow any of those officers' testimony to influence the cases they present against them.

That means removing the current prosecutors, who have handled the case since its inception, and installing a new team that has been instructed to avoid details of Nero's trial. The email, the sources said, instructs other prosecutors in the office not to speak to the attorneys about the case.

The state's attorney's office declined to comment due to a gag order in the case.

The prosecutors currently handling the cases, Chief Deputy State's Attorney Michael Schatzow and Deputy State's Attorney Janice Bledsoe, sought to have Porter compelled to testify against his fellow officers, under limited immunity that prevents his testimony from being used at his trial.

In granting the motion to compel Porter to testify, Williams warned prosecutors that they were headed down a tricky path in retrying Porter, whose trial ended in a mistrial in December. The move was unprecedented in Maryland, but affirmed by the state's highest court on appeal. Following that ruling, prosecutors also compelled the testimony of Miller.

The attorney general's office argued in support of the prosecutors' efforts, but also said that prosecutors were taking on a “substantial burden” at Porter's retrial. That it is “uncharted territory speaks volumes about the burden the state faces,” Assistant Attorney General Carrie Williams said.

Phelps has been with the state's attorney's office since 1999, and currently leads the training division. She was previously chief of the special victims unit, and a supervisor in the felony unit. David is listed as a prosecutor in the misdemeanor unit.

The court will likely hold a proceeding before Porter's retrial, called a “Kastigar hearing,” in which the burden would be on prosecutors to prove that they had not improperly used anything from Porter's testimony in preparation for their second run at prosecuting Porter.

Observers said having new prosecutors take over was the only way to prove to a judge that the officers' compelled testimony wasn't considered.

“I believe in order to do this in a way to avoid problems later, you have to have a different prosecution team at each of these trials,” said David Schertler, a Washington defense attorney who was part of the case against a Blackwater security guard, accused in a fatal shooting in Iraq, in which similar issues were raised.

University of Baltimore law professor David Jaros said he thinks the current attorneys on the case “shouldn't even be briefing or explaining the case to any other attorneys” once the testimony has occurred, he said.

jfenton@baltsun.com