A judge presiding over the trial of Daniel Penny, a former Marine accused of choking a homeless man to death on a New York City subway, has dismissed a charge of second-degree manslaughter against him, after jurors failed to reach an agreement.

New York jurors still have one less severe charge of criminally negligent homicide to consider.

On the fourth day of deliberations, the 12 jurors sent two notes saying they were "unable to come to a unanimous vote" on the first count, which would be required for a conviction.

The judge sent them back to try again, but they still could not agree, prompting prosecutors to ask the judge to dismiss the manslaughter count.

Mr Penny faced two charges over the killing of 30-year-old Jordan Neely on a subway in May 2023.

Prosecutors say Mr Penny held Mr Neely in a fatal chokehold for six minutes after restraining him on the subway. Mr Penny's attorneys say he was trying to protect others on the train, after Mr Neely began asking for money and screaming that he was hungry and wanted to go back to jail.

His death sparked continuing protests across the city. Occasionally, protestors' chants in support of Mr Neely could be heard in the 13th floor courtroom.

After receiving the first note from the 12 New York jurors, Judge Maxwell Wiley told them it made sense it was taking days for jurors to weigh the case.

"That's a long time, but given the factual complexity of the case, I don't think it's too long," he said, before sending them back to deliberate further.

After a second note from jurors saying they remained deadlocked, the top count of manslaughter was dismissed and the judge sent them back to deliberate yet again.

"You are now free to consider count two. Whether that makes any difference or not, I have no idea," he said.

The jury will return next week to continue its deliberations.

The manslaughter charge would have carried a 15-year maximum sentence, while the negligent homicide charge has a four-year-maximum.

Mr Penny's month-long trial featured a host of evidence, including bystander videos of the chokehold, 911 calls and police body camera footage, as well as testimony from witnesses and people from Mr Penny's past.

Members of Mr Neely's family have watched in the courtroom as the video of the subway incident was played over and over. Mr Neely's father also filed a civil suit against Mr Penny.

Mr Neely was a Michael Jackson impersonator known throughout the city for his performances in Times Square.

He had dozens of previous arrests on charges such as evading fares, theft and assaults on three women.

Family members said his mental health issues began more than 15 years earlier, when his mother was strangled by her boyfriend.