Cases normally are added to the list after prosecutors provide police with autopsy results from the state medical examiner. It's a routine step in all cases authorities investigate together.
But in Gray's case, police have not received autopsy information beyond details shared by Mosby when she announced the charges against the officers at a news conference on May 1.
Mosby said "the manner of death deemed a homicide by the State Medical Examiner is believed to be the result of a fatal injury that occurred while Mr. Gray was unrestrained by a seatbelt in the custody of the Baltimore Police Department wagon."
A spokesman for the medical examiner's office said state law requires only that the office to deliver autopsy information to prosecutors.
"As a matter of courtesy, it used to be provided to the police as well," spokesman Bruce Goldfarb said. But the practice stopped in recent years, he said, out of concern that autopsy information was being circulated too widely.
The medical examiner now provides two copies of an autopsy to the State's Attorney's Office, one with a letter that says prosecutors "may provide this to law enforcement at your discretion when you feel it's appropriate," Goldfarb said.
Police spokesman Capt. Eric Kowalczyk said police have not received the autopsy findings on the manner of Gray's death. But after receiving inquires from The Baltimore Sun, they added the case based on the criminal charges, saying it was clear it met the criteria.
The circumstances underscore divide between the agencies on the high-profile case. Police initially announced a May 1 deadline to finish their investigation of the case, with prosecutors noting that they had no such timetable for a decision on possible charges.
But when police wrapped their investigation a day early, they were stunned the next day to find out prosecutors were filing charges. Police Commissioner Anthony W. Batts told CNN he found out 10 minutes before the announcement.
The Sun has reported that police never locked onto an explanation for Gray's spinal injury, and planned to continue investigating. The parallel investigation being conducted by Mosby's office, in conjuction with the Baltimore City Sheriff's Office, concluded the case merited serious criminal charges - including second-degree murder and manslaughter - and cited the medical examiner's finding of homicide as the cause of death.
Those investigators have seen the autopsy - police have not.