A former US Marine is to be charged with the manslaughter of a homeless man on the New York City subway, the Manhattan district attorney has said.

Daniel Penny, 24, will be arrested and formally accused on Friday of causing Jordan Neely's death after he placed the 30-year-old in a chokehold.

Mr Penny's lawyers say he could not have known his actions to subdue Mr Neely would lead to his death.

The incident on Monday 1 May was captured on mobile phone footage.

"We can confirm that Daniel Penny will be arrested on a charge of manslaughter in the second degree," said a spokesperson for the Manhattan District Attorney's Office in a statement.

"We cannot provide any additional information until he has been arraigned in Manhattan criminal court."

Witnesses said Mr Neely was acting aggressively towards other subway passengers, but he had not physically attacked anyone before Mr Penny put him in a chokehold.

A video captured by a freelance journalist on the train shows the former Marine holding the Mr Neely around the neck for two minutes and 55 seconds.

Mr Penny told other riders to call 911 during the struggle with Mr Neely, according to CBS News, the BBC's US partner.

The ex-Marine was questioned and released by police in New York on the day of the incident.

In a statement earlier this month, lawyers for Mr Penny expressed condolences to the Neely family, and said Mr Penny and other passengers acted in self-defence.

They said Mr Neely's behaviour was "the apparent result of ongoing and untreated, mental illness", which prompted Mr Penny and others "to protect themselves, until help arrived".

It is not clear whether charges will be brought against two other unidentified people who were also seen restraining Mr Neely in the online video.

A witness to the altercation said Mr Neely was shouting about being hungry and thirsty. Police sources also told CBS News that Mr Neely was allegedly acting erratically.

In a statement earlier this week, Mr Neely's family said that Mr Penny "needs to be in prison".

"The family wants you to know that Jordan matters," they said.

Mr Neely was a Michael Jackson impersonator who frequently performed in Times Square.

He had a number of previous offences, which New York City Mayor Eric Adams said highlights the need to improve the mental health system so that it can better protect people like him.

Mr Neely had 42 arrests on charges such as evading fares, theft, and assaults on three women, according to US media reports.

His mother, Christie Neely, was murdered in 2007 by her boyfriend, who was sentenced to 30 years in prison in 2012, according to the Jersey Journal.

Following his mother's death, Mr Neely began experiencing mental health issues, his aunt, Carolyn Neely, told the New York Post.

His death sparked protests across the city and calls for justice.

The New York City medical examiner ruled Mr Neely's death a homicide that resulted from "compression of [the] neck". (BBC)

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