A US court has ruled that a police officer must testify in the cases of colleagues charged over the custody death of Freddie Gray, local media say.
Policeman William Porter himself went on trial in the case last year but a mistrial was declared and a fresh trial has been set for later this year.
His lawyers had argued that making him testify in other cases would violate his right not to incriminate himself.
Gray’s death sparked unrest and weeks of protests in Baltimore.
Officer Porter’s evidence in the other cases will not be permissible as evidence against him in his own retrial.
Tuesday’s ruling from Maryland’s highest court means that the trials of the other five officers, Caesar Goodson, Sgt Alicia White, Edward Nero, Garrett Miller and Lt Brian Rice, can now move forward.
They face various charges including manslaughter, assault and misconduct in office. They deny all charges.
It is not clear whether Officer Porter’s lawyers will seek to appeal against the ruling in the US Supreme Court.
Gray was arrested on 12 April 2015 after a police chase on foot in West Baltimore. He sustained a severe spinal injury while being transported in a police van.
Police later admitted he had not been secured by a seatbelt and his request for medical attention at the time was denied. He fell into a coma and died a week later.
His death sparked protests over police brutality, with the city of Baltimore erupting in rioting, looting and arson on the day of his funeral.
Along with several others, his death quickly became a flashpoint in a national debate over police use of force – especially against black men.
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