0318 GMT June 20, 2019
Caesar Goodson was with Freddie Gray for every second of his 45-minute trip to the Western District police station, where Gray arrived critically injured and unresponsive.
Goodson's trial will begin on Monday. He is the only one of six officers charged in Gray's death not to speak to investigators.
Goodson was the driver of the van that carried Gray to six different locations while he was handcuffed and shackled but unrestrained in the back of the vehicle.
He faces a second-degree murder conviction, the most serious charge of all, which carries a maximum sentence of 30 years in prison.
Last month, the trial of Baltimore police officer William Porter ended with a deadlocked jury.
Prosecutors say the officers should be held accountable for Gray's fatal injuries because they didn't buckle him into a seat belt, nor did they call an ambulance when he indicated he needed medical attention.
Gray, 25, died on April 19, a week after an encounter with police that left him with grave spinal injuries.
His death exposed the tense relations between the public and the police in the US, and became a national symbol of the Black Lives Matter movement protesting police brutality against minority communities.
Analysts believe tensions between police and citizens have reached an all-time high in recent years over the use of excessive force by police, particularly against minorities.