Maryland prosecutors appeal to force testimony in Freddie Gray case

Gloria Darden (L), mother of the late Freddie Gray, listens to media questions during a family news conference outside the courthouse in Baltimore, December 16, 2015. REUTERS/Bryan Woolston

(Reuters) - Maryland prosecutors have asked an appeals court to force a Baltimore police officer to testify against three of his colleagues in the Freddie Gray case, according to a filing made public on Friday.

The Court of Special Appeals document filed on Thursday says prosecutors are appealing Baltimore City Circuit Court Judge Barry Williams' Jan. 20 ruling that blocked them from calling Officer William Porter to testify against Edward Nero and two other officers.

The four are among a half-dozen officers charged in the death of Gray, a 25-year-old black man. His death in April 2015 from an injury sustained while in police custody triggered protests and rioting and intensified a U.S. debate on police treatment of minorities.

Nero is charged with second-degree assault, misconduct in office and reckless endangerment. His trial is scheduled to start on Feb. 22.

Trials of the other two officers, Garrett Miller and Lieutenant Brian Rice, are set for March. Porter's manslaughter trial ended in a hung jury in December, and a retrial is scheduled for June.

The Court of Special Appeals delayed the murder trial of another officer, Caesar Goodson Jr., last month until it can decide whether Porter can be compelled to testify against him and the sixth officer, Sergeant Alicia White.

Williams had ordered Porter to testify since he had been offered immunity from prosecution for what he might say on the stand.

(Reporting by Ian Simpson; Editing by Sandra Maler)