because he was not belted in and his wrist and ankles were shackled making him at risk for an unsupported fall. the m.e. believes freddie gray was trying to get to his feet and when the van slowed down gray slammed his head against the wall severing his spine. here's the deputy police commissioner. >> i know that when mr. gray was placed inside that van, he was able to talk he was upset and when mr. gray as taken out of that van, he could not talk and he could not breathe. >> six baltimore police officers have been charged with assault. four of them are also charged with involuntary manslaughter. officer goodson, the driver of the van is the only officer charged with second degree murder. prosecutors have now turned over 300,000 pieces of evidence. that's 52 gigabytes of digital files, the equivalent of 26 hours of high definition video. among the evidence are statements from 15 civilian witnesses, four surveillance videos four cell phone videos, blood samples from the back of the police van and 8,000 pages of the accused officers' e-mails. defense attorneys are calling for a change of venue b