Except he didn't. Freddie Gray didn't die until a week later, in the hospital.
Depends on what you mean by "die." The other guy in the van testified that when they got to the jail, the cops were saying Gray had no pulse. So the paramedics probably had to shock his heart and then they kept him on artificial respiration for a week in the hospital, while his body was in a vegetative state, before they simply pulled the plug and finally declared him dead.