Police van driver Caesar Goodson was with Freddie Gray for every second of his 45-minute trip from the site of his arrest to the Western District police station, where Gray arrived critically injured and unresponsive. But Goodson's account of what happened on that day remains a mystery. He is the only one of six officers charged in Gray's death not to speak to investigators.

His trial begins Monday and will offer the public its first chance to hear Goodson's side of the story.

Goodson faces the most serious charge of all six officers: second-degree "depraved-heart" murder. To be convicted, prosecutors must prove that Goodson was so callous in his disregard for Gray's life that he deliberately allowed him to die.