Freddie Gray died from spinal trauma a week after being arrested by a group of officers, hoisted into police van and driven to a Baltimore station. According to a lawyer for the officer's union, Gray wasn't strapped in with a seatbelt.

Failing to belt an inmate would violate a policy on handling detainees issued by their own department just nine days prior.

The document, released by a police department spokesman, states that officers should "ensure the safety of the detainee" and that "all passengers, regardless of age and location, shall be restrained by seat belts or other authorized restraining devices."

Assistant Police Commissioner Jerry Rodriguez said Gray was secured by "leg irons" after he became agitated during the trip, but the department hasn't said whether he was left otherwise unsecured, as Attorney Michael Davey, who represents at least one of the officers under investigation, told The Associated Press.

Davey acknowledged that department policy requires seatbelts, but said "policy is policy, practice is something else," particularly if a prisoner is combative.

"It is not always possible or safe for officers to enter the rear of those transport vans that are very small, and this one was very small," Davey said.

That April 3rd policy, updating a 1997 policy that also required detainees to be secured, is standard nationwide, said Robert Stewart, a former police chief who consults with departments and the Department of Justice on procedures the use of force. Stewart said strapping them in with seatbelts is "not the Torah," but should be adhered to whenever feasible.

Gray fled and was captured by police on April 12 after one officer "made eye contact" with him. Video recordings outside the public housing complex outfitted with surveillance cameras show Gray screaming on the ground then being dragged, his legs limp, into a van.

Witnesses have said Gray was crying out in pain when he was loaded into the wagon.

Roughly 40 minutes then passed before police said Gray was taken to a hospital in critical condition with the severe spinal injury that led to his death a week later.

Davey said he believes the fatal injury happened inside the police van. The assistant commissioner suggested as much as well.

"I know that when Mr. Gray was placed inside that van he was able to talk, he was upset," Rodriguez said Monday at a news conference. Rodriguez said Gray became "irate" and that the van stopped so that officers could shackle his legs. Then, "when he was taken out of that van, he could not talk and he could not breathe."

But Stewart, the police practices consultant, cautioned against focusing solely on how Gray was transported.

"How did his injuries occur?" Stewart said after watching the videos. "These guys are picking up someone who is obviously injured."

The same policy requires arresting officers to determine if medical help is needed and take care not to aggravate any injury. The driver also has a role, and should refuse to take a seriously injured prisoner to the station if he belongs in a hospital.

"If I'm the officer in the wagon, if the guy's hurt, I'm not taking him," Stewart said.

All six officers involved in Gray's arrest have been suspended with pay and are under criminal investigation. Davey, whose law firm is on contract with the Baltimore Fraternal Order of Police Lodge 3, said five of the six officers gave voluntary statements the day of Gray's arrest, and one declined to speak with investigators.

The transport policy clearly states that arresting officers must "ensure medical treatment for a detainee is obtained, when necessary or requested, at the nearest medical facility."

Commissioner Anthony Batts said Gray repeatedly requested medical attention during the ride, and that only after arrival at the Western District station house were paramedics called.

"There were several times he made a medical request," Batts said Monday. "He asked for an inhaler, and at one or two of the stops it was noticed that he was having trouble breathing, we probably should have asked for paramedics."

Earlier this week the Department of Justice announced that it has opened an investigation into Gray's death to determine whether his civil rights had been violated. Rodriguez said the department's investigation will be completed by May 1 and delivered to the state's attorney's office to consider filing any criminal charges.