A Staten Island grand jury has cleared an NYPD officer of criminal wrongdoing in the chokehold case of Eric Garner, the unarmed man who died while being arrested in the borough earlier this year, the district attorney's office said Wednesday.

In delivering a vote of "no true bill," jurors determined there was not probable cause that a crime was committed by NYPD officer Daniel Pantaleo, who was seen on a widely watched amateur video wrapping his arm around Garner's neck as the 43-year-old yelled, "I can't breathe!" during the July 17 confrontation.

U.S. Attorney General Eric Holder announced Wednesday that the Justice Department will now be conducting its own investigation into Garner's death, and that prosecutors will also conduct a complete review of the material gathered during the local investigation.

"We have all seen the video of Mr. Garner's arrest. His death, of course, was a tragedy," he said.

"Mr. Garner's death is one of several recent incidents across the country that have tested the sense of trust that must exist between law enforcement and the communities they are charged to serve and protect," Holder added. "This is not a New York issue or a Ferguson issue alone."

Garner, who had been stopped by Pantaleo and several other NYPD officers, including two sergeants, on suspicion of selling loose, untaxed cigarettes, was pronounced dead at a hospital.

The medical examiner ruled Garner's death a homicide caused in part by the chokehold. The father of three's health issues, including obesity, were listed as contributing factors in the autopsy report.

Pantaleo was the only officer facing potential charges. He has been on modified desk duty and doing crime analysis statistics since Garner's death, according to his attorney, Stuart London. The other officers at the scene that summer day were offered immunity for their testimony to the grand jury.

In a statement, Pantaleo said he never intended to harm anyone.

“I became a police officer to help people and to protect those who can’t protect themselves," Pantaleo said. "It is never my intention to harm anyone and I feel very bad about the death of Mr. Garner. My family and I include him and his family in our prayers and I hope that they will accept my personal condolences for their loss.”

Garner's family told NBC News they were angry and frustrated by the grand jury's vote, and thought the video showing Garner's arrest was indisputable proof of wrongdoing.

"There's no doubt in my mind or the mind of all the people out there in the world that what we saw in that video cannot be disputed," said Garner's wife, Esaw Garner. "How they disputed it, I don't know."

The Rev. Al Sharpton, who has been representing the family, announced in a news conference Wednesday evening that the Garners will be helping to lead a national march in Washington, D.C. on Saturday, Dec. 13.

"It is time for a national march to deal with a national crisis," he said.

The grand jury could have considered a range of charges, from a murder charge to a lesser offense like reckless endangerment. It wasn't clear what charges the jurors had considered.

In a statement, Staten Island District Attorney Daniel Donovan offered his condolences to Garner's family and friends "who have consistently carried themselves with grace during the past four months" and thanked the grand jurors for their commitment to the investigation "and for the careful manner in which they discharged their solemn duty."

"Clearly this matter was of special concern in that an unarmed citizen of our County had died in police custody," Donovan said, adding that is why he convened a special grand jury to hear the case. "All 23 members of this community who comprised the Grand Jury in this matter dutifully fulfilled that commitment by attending each and every one of the sessions that began on September 29, 2014, and concluded on December 3, 2014."

Garner's mother and widow were expected to hold a news conference with the Rev. Al Sharpton later Wednesday. Previously, relatives said the video and medical examiner's report should be enough to warrant an indictment. Police union officials and Pantaleo's lawyer had 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.

After the grand jury decision Wednesday, Patrolmen's Benevolent Association President Patrick Lynch said the union was pleased, but "there are no winners here today."

"There was a loss of life that both a family and a police officer will always have to live with," Lynch said. "No police officer starts a shift intending to take another human being's life and we are all saddened by this tragedy.”

The case 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.

The jurors' decision comes about a week after they heard testimony from Pantaleo, one of their last witnesses from whom they heard for about two hours, and several months after they were impaneled to hear evidence. On Staten Island, grand jurors are permitted to call out questions, and London told MSNBC they asked about 20 of the police officer while he was on the stand.

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.

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

Crowds began gathering Wednesday evening at the Tompkinsville site where Garner died and more than 100 people protested the grand jury decision by lying on the floor of Grand Central Terminal as police fanned across the five boroughs to secure the demonstrations.

Ahead of the anticipated rallies, Mayor de Blasio called for "peaceful, constructive" means of expression on this "deeply emotional day."

"We all agree that demonstrations and free speech are valuable contributions to debate, and that violence and disorder are not only wrong -- but hurt the critically important goals we are trying to achieve together," the mayor said.

Garner's mother Gwen Carr echoed the sentiment at the news conference led by Sharpton.

"Make a statement, but make it in peace," she pleaded to supporters, adding that "this thing is just breaking my heart, it's pulling me apart."

De Blasio said the NYPD has begun implementing long-term reforms this year to "ensure we don't endure tragedies like this one again in the future. But we also know that this chapter is not yet complete."

The NYPD internal investigation into Garner's death is ongoing, the mayor said.

The U.S. Department of Justice is also investigating and should the federal government choose to indict, de Blasio said New York City would cooperate.

"All of us must work together to make this right - to work for justice - and to build the kind of city -- and nation -- we need to be," he said.

President Obama, who met with de Blasio and Sharpton at the White House Monday as part of a series of meetings on Ferguson, echoed the mayor's comments Wednesday. He said the nation has been dealing with mistrust between communities of color and police for too long and pledged to work with local governments in those communities to bridge the gaps -- in perception and reality.

"I want to know here that we are not going to let up until we see strength of trust and strength of accountability between communities and law enforcement," Obama said.

Garner's wife, Esaw Garner, vowed at the family's news conference, "My husband's death will not be in vain. As long as I have a breath in my body, I will fight the fight till the very end."

In New York, the grand jury does not hear opening or closing statements from the district attorney, who simply presents evidence and instructs them on the relevant principles of the law they need to make their decision on whether charges should be filed. To formally charge a person with a crime, at least 12 grand jurors who have heard all the evidence and the legal instructions must agree that there is sufficient evidence and reasonable cause to believe a crime was committed.

Donovan could not disclose further details of the case because of New York law surrounding grand juries, but said he had applied for a court order seeking authorization to publicly release specific elements of the proceedings. The application is under court consideration, he said.

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.