The department will not release personnel records or photos because doing so would violate the law, the police said in a statement.
"They have completely cooperated with the investigation from Day 1," Michael Davey, an attorney for the officers involved, told reporters.
He defended their interactions with Gray, and said that police did not need probable cause to arrest.
"There is a Supreme Court case that states that if you are in a high-crime area, and you flee from the police unprovoked, the police have the legal ability to pursue you, and that's what they did," he said. "In this type of an incident, you do not need probable cause to arrest. You just need a reasonable suspicion to make the stop."
The department released the officers' names earlier: Lt. Brian Rice, 41, who joined the department in 1997; Officer Caesar Goodson, 45, who joined in 1999; Sgt. Alicia White, 30, who joined in 2010; Officer William Porter, 25, who joined in 2012; Officer Garrett Miller, 26, who joined in 2012; and Officer Edward Nero, 29, who joined in 2012.
Of the six officers, three were on bikes and initially approached Gray, another made eye contact with Gray, another officer joined in the arrest after it was initiated and one drove the police van, Capt. Eric Kowalczyk said.
Another person, who was inside the prisoner transport van carrying Gray, is a witness in a criminal investigation, so his name won't be released, police said.
"The investigation, as it stands, will be turned over to the State's Attorney's Office for review on May 1, 2015," the statement said. "As with any criminal investigation, detectives will continue to pursue the evidence wherever it leads, for as long as it takes."
The emotions are raw and protests are growing in Baltimore, where a community wants answers in the Gray's death.
As protesters chanted, "No justice, no peace!" Tuesday evening, Gray's distraught mother, Gloria Darden, collapsed in tears at the spot where her son was arrested this month. She was whisked away.
Gray, a 25-year-old black man, died of a spinal injury on Sunday, one week after he was taken into custody.
The demonstrations are gaining momentum. The crowd was back late Wednesday, and on Thursday, a rally is planned in front of City Hall.
"We won't stop," one man said Tuesday. "We have the power and, of course, today shows we have the numbers."
Baltimore Mayor Stephanie Rawlings-Blake said she understands where the protesters are coming from. She understands their frustration.
"Mr. Gray's family deserves justice, and our community deserves an opportunity to heal, to get better and to make sure that something like this doesn't happen again," she said.
But not everyone is pleased by the presence of protesters. A statement from the Fraternal Order of Police Lodge 3 compared the demonstrations to a "lynch mob."
"While we appreciate the right of our citizens to protest and applaud the fact that, to date, the protests have been peaceful, we are very concerned about the rhetoric of the protests. In fact, the images seen on television look and sound much like a lynch mob in that they are calling for the immediate imprisonment of these officers without them ever receiving the due process that is the constitutional right of every citizen, including law enforcement officers," it read.
Feds getting involved
The increasing public pressure comes as the Department of Justice announced it was opening an investigation into the case.
A spokesman said the agency is investigating whether Gray's civil rights were violated during the April 12 arrest.
An autopsy found that Gray died from a spinal cord injury, but Baltimore Deputy Police Commissioner Jerry Rodriguez told reporters Monday that there is no indication how the injury occurred.
"We welcome outside review," Kowalczyk said. "We want to be open. We want to be transparent. We owe it to the city, and we owe it to the Gray family to find out exactly what happened."
It will be up to the state's attorney's office to decide whether to file charges.
Adding to the community's frustration is an autopsy that hasn't yielded many answers in Gray's death
. In fact, some feel it's prompted more questions.
"I'm going to make sure that as we get information that we can confirm, we're going to put that information out in the public," Rawlings-Blake said. "I want people to understand that I have no interest in hiding information, holding back information."
She's angry, she said, and among the questions she wants answered are: Why did police stop Gray in the first place? And why did arresting officers make what she called the mistake of not immediately requesting medical attention when Gray asked for it?
"We will get to the bottom of it, and we will go where the facts lead us," she said. "We will hold people accountable if we find there was wrongdoing."
The mayor has requested a meeting with the Gray family, but the Grays declined, saying they were focused on funeral arrangements, so the timing wasn't appropriate, said Zach McDaniel, who is part of the family's legal team.
Family attorney William Murphy urged patience in the case and called for a careful investigation.
"Now am I skeptical of the police investigation? You bet. Do I have reason to be skeptical? Yes. I am a normal human being who understands the history of the relationship between white police and black people in this country," he said. "That's enough to make me skeptical."
What we know
According to documents, the incident began when Gray ran from police.
While the court documents allege that one of the arresting officers, Miller, took Gray into custody after finding a switchblade in his pocket, Murphy called the allegation a "sideshow." Gray was carrying a "pocketknife of legal size," he said.
Police never saw the knife and chased Gray only after he took off running, the attorney said.
Court documents say Gray "fled unprovoked upon noticing police presence."
"The officer noticed a knife clipped to the inside of (Gray's) front right pants pocket. The defendant was arrested without force or incident," the documents say. "The knife was recovered by this officer and found to be a spring assisted, one-hand-operated knife."
The mayor has questioned whether police should have pursued Gray in the first place.
"It is not necessarily probable cause to chase someone. So we still have questions," Rawlings-Blake said.
Gray was in perfect health until police chased and tackled him, Murphy said. Less than an hour later, he was on his way to a trauma clinic with a spinal injury, where he fell into a coma.
The family has not seen the autopsy report yet, Murphy said. The medical examiner's office told CNN it could take up to 90 days to release the report, which is typical.
On Wednesday afternoon, the medical examiner cleared the body to be released to the family, Gray family co-counsel Jason Downs said. The family intends to have a second, private autopsy conducted once Baltimore police turn over the body, the attorney said.
What the police say
Police, according to their own timeline
, spotted Gray, gave chase, caught him, cuffed him and requested a paddy wagon in fewer than four minutes.
"The officers that I saw there were not out of control. They weren't causing him any pain ... And when they lifted him up they grabbed him under his armpits and they moved him as best they can," Police Commissioner Anthony Batts told CNN affiliate WJZ
The transport van left with Gray about 11 minutes afterward, police said, and another 30 minutes passed before "units request paramedics to the Western District to transport the suspect to an area hospital."
Murphy and angry residents of Baltimore want to know what happened in those 30 minutes.
When cell phones began recording, Gray was already on the ground with three officers kneeling over him. He let out long screams.
"Our position is something happened in that van. We just don't know what," said Davey, the attorney representing the officers involved in the incident.
He also said he does not think Gray was wearing a seat belt inside the van he was placed in after his arrest.
Police said Gray requested medical attention, including an inhaler, and an ambulance took him to the University of Maryland Medical Center's Shock Trauma Center.
"He lapsed into a coma, died, was resuscitated, stayed in a coma and on Monday underwent extensive surgery at Shock Trauma to save his life," Murphy said. "He clung to life for seven days."