A New York City grand jury decided not to charge a white police officer in the chokehold death of an unarmed black man, sparking outrage and protests on Wednesday, and the US Justice Department said it would investigate the incident. Eric Garner, a 43-year-old father of six, was accused of illegally selling cigarettes on July 17 when police officers tackled him and put him in a chokehold. Police said he had been resisting arrest. The city’s medical examiner previously ruled the death a homicide. The deadly encounter on Staten Island, New York City’s smallest borough, was captured on video, which quickly spread over the Internet and fueled debate about how US police use force, particularly against minorities. It was the second grand jury in just over a week to decline to prosecute a white policeman in the death of an unarmed black man. The decision by grand jurors in Ferguson, Missouri, in the death of black teenager Michael Brown sparked a spasm of violence, with businesses burned and looted. On Wednesday, about two dozen demonstrators lay down in Grand Central Terminal’s main hall in Midtown Manhattan in a silent protest as the evening rush hour began. Similar “die-in” protests cropped up around Manhattan, including near where the Rockefeller Center Christmas tree lighting ceremony was under way. Police blockaded the street, preventing marchers from interrupting the nationally televised event. In Times Square, hundreds of protesters gathered for a time and then moved on, chanting “No indictment is denial. We want a public trial.” A handful of protesters were arrested there, according to a Reuters witness. On Staten Island, near the site where Garner was apprehended, Garner’s stepfather Ben Carr consoled an angry man in a car. “We don’t want no Fergusons here,” Carr said, referring to the riots that erupted in the St. Louis suburb last week after that grand jury’s decision. “All we want is peace.” The Justice Department said it would investigate the Garner case. It is already probing the circumstances of the Missouri shooting. “Our prosecutors will conduct an independent, thorough, fair and expeditious investigation,” US Attorney General Eric Holder told reporters in Washington. “In addition to performing our own investigative work, the department will conduct a complete review of the material gathered during the local investigation.” Legal experts say that while there is no explicit law against chokeholds, their use is prohibited by New York police regulations. Any violation, however, would not necessarily constitute a crime, they said. The Patrolmen’s Benevolent Association, the municipal police union, says the officers involved in the Garner incident acted within the scope of the law. Mayor's warning to son President Barack Obama, while not directly commenting on the case, said the grand jury decision spoke to “the concern on the part of too many minority communities that law enforcement is not working with them and dealing with them in a fair way. “We are not going to let up until we see a strengthening of trust and strengthening of accountability that exists between our communities and our law enforcement,” he said. The grand jury decision poses the biggest challenge yet for New York Mayor Bill de Blasio, who came into office in January promising to improve relations between black New Yorkers and the police department. On Wednesday, he praised New York police commissioner Bill Bratton’s efforts to bridge the divide. However, he also said he had warned his African-American son to take “special care in any encounters with police officers.” The district attorney for Staten Island, Daniel Donovan, announced the grand jury’s decision not to indict the police officer, Daniel Pantaleo, who had placed Garner in a chokehold. “It is never my intention to harm anyone and I feel very bad about the death of Mr. Garner,” Pantaleo said in a statement released by the Patrolmen’s Benevolent Association union. Pantaleo testified at the grand jury. It is rare for defendants to testify in such proceedings but prosecutors have discretion to decide which witnesses to call and can choose to put a police officer accused of misconduct on the stand. The officer in the Michael Brown shooting also testified to the Missouri grand jury. Benjamin Carr, the stepfather of Garner, said he was distraught over the verdict. “The justice system didn’t do what it was supposed to do,” he said at the site where Garner was apprehended by police and a makeshift memorial now stands. Tempers flared at the site as about a dozen protesters expressed their anger at the grand jury’s decision. Daniel Skelton, a black 40-year-old banker, spoke loudly as he voiced his outrage at the grand jury verdict. “A black man’s life just don’t matter in this country,” he said. Police prosecutions rare It is rare for either federal or state prosecutors to charge a US police officer for excessive force, even when a death results. The US Supreme Court and lower courts have ruled over decades that police officers should have wide latitude to use violence to defend themselves and to take suspects into custody. “What’s so shocking about this grand jury decision for most folks is that the evidence on the video tape seemed so clear, but grand jurors will very often give the police officers the benefit of the doubt,” said Vincent Warren, the executive director of the Center for Constitutional Rights. “They treat them not as citizens but as super citizens.” In ruling Garner’s death a homicide, the city medical examiner said police officers killed him by compressing his neck and chest. His health problems, including asthma and obesity, were contributing factors, the medical examiner said. The video of Garner’s arrest shows him arguing with police officers, saying, “Please leave me alone,” and later, “Don’t touch me,” before Pantaleo puts him in a chokehold from behind and tackled him to the ground with three other officers. He then began to plead with them, saying repeatedly, “I can’t breathe.”