The investigation into Freddie Gray's death is now focusing on the van that police used to transport him to a police station, a source has told NBC Washington.
The investigation is looking into the possibility that the van is where Gray's fatal injuries happened, according to the sources. What brought about those injuries is still unclear.
Gray suffered severe spinal injuries after being stopped by police April 12 and died a week later.
Gray's condition while in the van has become a critical and contested part of the story. A Washington Post report published Wednesday night said a prisoner being transported with Gray heard Gray "banging against the walls” of the van, according to a police documents. The prisoner said Gray was "banging against the walls" and that he believed Gray "was intentionally trying to injure himself."
The document the Post obtained was written by a Baltimore police investigator and it is unknown if there is additional evidence to support the claim.
A Baltimore man who told NBC affiliate in Baltimore, WBAL, that he was transported in a police van with Gray, gave the station a slightly different account from one described in the Post.
"All I heard was a little banging for like, four seconds," Allen said. "Just a little banging."
Allen told WBAL that when the van arrived at the West Baltimore police station, he heard officers saying Gray didn't have a pulse. "They were calling his name, 'Mr. Gray, Mr. Gray, and he wasn't responsive," Allen said.
Meanwhile, Baltimore police have completed their criminal investigation into Gray's death and delivered it to a prosecutor a day earlier than promised. Police Commissioner Anthony Batts said Thursday his department stands ready to help the state's attorney gather more evidence.
As if to drive home that point, a deputy commissioner revealed a piece of information that raises still more questions about what the officers involved have told investigators: The police van carrying Gray to the station made a previously undisclosed stop that was captured on a "privately owned camera."
State's Attorney Marilyn Mosby must review the evidence, consider charges and decide how to move forward in the death of Gray, who suffered severe spinal injuries after being stopped by police April 12 and died a week later. His death has touched off days of protests, some violent, in Baltimore and in other cities around the country, including D.C.
According to charging documents filed by police in the case and obtained by NBC News Thursday, Gray was arrested in Baltimore for possession of a switchblade and "without force or incident." The hand-written documents give little information that was not already available about Gray's arrest.
The officer who wrote the report, listed as "G. Miller," said Gray was arrested after he "fled unprovoked upon ... noticing police presence." After a chase, an officer noticed a knife clipped to the inside of Gray's front right pants pocket.
Earlier this week, Baltimore police said Officer Garrett Miller was among six officers suspended with pay while authorities investigate the death.
The documents note that "during transport to Western District via wagon transport the defendant suffered a medical emergency and was immediately transported to shock trauma.” It makes no mention of stops en route, though police have now said the van stopped four times between the time officers arrested Gray and his arrival at the police station.
Batts took no questions and provided no details about the report, which he said represents the work of more than 30 investigators.
"I understand the frustration; I understand the sense of urgency," Batts said. "That is why we have finished it a day ahead of time."
Batts said nothing more about when or how investigators obtained the previously undisclosed video or learned about the additional stop. However, five of the six officers gave statements to investigators the day Gray was injured, and as recently as a week ago, the stop was not part of the official timeline, suggesting investigators learned of it later.
Gray was arrested after he made eye contact with an officer and ran. Officers chased him down and handcuffed him behind his back. Bystander videos recorded police loading him, dragging his legs, into one of two metal compartments in the back of the van.
Police earlier said the van stopped once so that officers could put Gray in "leg irons" because he had become "irate;" stopped again because the driver asked for an additional unit to check on Gray's condition, and then again to put an additional prisoner in the van's other compartment before arriving at the station.
Last week, Batts had said the second prisoner told investigators the driver did not speed, make sudden stops or "drive erratically" during the trip, and that Gray was "was still moving around, that he was kicking and making noises" up until the van arrived at the police station.
Mayor Stephanie Rawlings-Blake sought to dispel any notion that the police report would bring a swift and public conclusion to the case. "Whatever time the state's attorney's office needs to make that determination, the family wants to get it right," she said Wednesday after meeting with Gray's family and legal team.
"This family wants justice and they want justice that comes at the right time and not too soon," said Hassan Murphy, one of the family's lawyers.
Meanwhile, protests over Gray's death spread Wednesday night to other cities including Boston, New York and Washington, making it clear that tensions over the case are far from subsiding. The demonstrations were mostly peaceful, but police made many arrests, including at least 60 in New York.
Gray's death was only the latest high-profile case of a black man dying as the result of a police encounter. Similar protests erupted over the killings of Michael Brown in Ferguson, Missouri; Eric Garner in New York last year, and Walter Scott in South Carolina. Scott was shot in the back by a white officer who has since been charged with murder.