A New York City grand jury is expected to vote Wednesday on whether there was any criminal wrongdoing in the police chokehold death of Eric Garner, the unarmed man who was killed while being arrested on Staten Island earlier this year, multiple sources familiar with the court proceedings tell NBC 4 New York.

The grand jury that began investigating Garner's death in September heard late last month from who was believed to be its final witness -- NYPD officer Daniel Pantaleo. Pantaleo was seen on a widely watched amateur video wrapping his arm around Garner's neck as Garner yelled, '"I can't breathe!" during the summer altercation.

The panel has been tasked with deciding if Pantaleo will face criminal charges in the case, which grabbed national headlines and sparked outrage weeks before the shooting death of Michael Brown in Ferguson, Missouri, set off a firestorm over police tactics and race relations. Pantaleo is the only NYPD member facing possible indictment. Others at the scene, including two sergeants, were offered immunity for their testimony to the grand jury.

Of the 23 members of the Garner grand jury, 14 are white, nine are non-white and at least five are black, according to two people familiar with the grand jury's racial makeup. 

Stuart London, the attorney for Pantaleo, told MSNBC that the grand jurors listened attentively to Pantaleo as he testified for about two hours. On Staten Island, grand jurors may call out questions, and they asked Pantaleo more than 20 of them, London said.

Pantaleo is white, and Garner was black. Garner's family, in an effort to curb tensions, has consistently said race should not be a factor in the case, but protests in Ferguson have raised concerns in New York.

"It's not just Ferguson. We're dealing with Staten Island and Cleveland," said the Rev. Al Sharpton, who has been acting as a spokesman for the Garner family. "This is a national problem."

Mayor de Blasio, who met with President Obama along with Sharpton at the White House Monday as part of a series of meetings on Ferguson, said Tuesday, "In some places, people may feel the voice of the people are not heard. In this city, the voices are heard." 

The Garner case stems from a July 17 confrontation between Pantaleo and other NYPD officers who stopped the 43-year-old on suspicion of selling loose, untaxed cigarettes. Video shot by an onlooker shows Garner telling the officers to leave him alone and refusing to be handcuffed.

Pantaleo responded by putting Garner in an apparent chokehold, which is banned under NYPD policy. The heavyset Garner, who had asthma, is heard gasping, "I can't breathe." He later was pronounced dead at a hospital.

The medical examiner ruled Garner's death a homicide caused in part by the chokehold. Garner's health issues, including obesity, were contributing factors. 

Garner's family has said the video and medical examiner's report should be enough to warrant an indictment. Police union officials and Pantaleo's lawyer have argued that the officer didn't use a chokehold but a takedown move taught by the police department, and that Garner's poor health was the main reason he died.

Police Commissioner Bill Bratton said Tuesday police are preparing for protests in response to the Garner grand jury decision.

"We on the police side will naturally gear up to deal with any potential contingency that might occur," he said. 

Asked by NBC 4 New York Tuesday what he'd tell New Yorkers awaiting the grand jury decision, Staten Island District Attorney Daniel Donovan said, "I'd like New Yorkers to be patient. The grand jury has been diligently listening to evidence." 

Donovan said he realizes not everyone will accept the outcome, no matter what the grand jury votes.

"Regardless of what the decision is, there will be some demonstrations," he said. "We had a remarkably peaceful demonstration. It’s great to be in America where people can voice their opposition to something." 

Garner's mother, Gwen Carr, told NBC 4 New York last week she "wouldn't want to see that violence" that swept Ferguson.

"At this point, I'll just leave it in the hands of God," she said. 

Pantaleo is currently on modified desk duty and doing crime analysis statistics, according to London. 

The last time an NYPD officer was indicted in a deadly chokehold case was in 1995. In that case, a Bronx grand jury charged officer Francis Livoti with killing 29-year-old Anthony Baez in December 1994. Livoti waived his right to a jury trial and was acquitted by a state judge in 1996. Two years later, Livoti was convicted of criminally negligent homicide in federal court and sentenced to seven years in prison. He was released in 2005 after serving nearly the entire sentence.