Daniel Penny, the Marine veteran who choked and killed Jordan Neely, a homeless man, on the subway last week, surrendered on Friday to face a charge of second-degree manslaughter.

Mr. Penny, 24, dressed in a dark gray suit, walked through the front doors of the Police Department’s Fifth Precinct at around 8 a.m.

Mr. Penny encountered Jordan Neely, 30, on an F train on May 1 and placed him in a chokehold for several minutes, killing him. Witnesses said that Mr. Neely, who had a history of mental illness, was acting in a “hostile and erratic manner” toward other passengers on the train, according to the police, but there has been no indication that he physically attacked anyone before Mr. Penny began choking him.

The struggle on the F train was captured in a four-minute video that showed Mr. Penny continue to choke Mr. Neely for an additional 50 seconds after Mr. Neely had stopped moving. The police interviewed Mr. Penny that night, but initially released him without charging him.

A week and a half later, on Thursday, the Manhattan district attorney’s office confirmed that it planned to charge Mr. Penny in the killing.

Mr. Penny’s lawyers, Steven M. Raiser and Thomas A. Kenniff, said in a statement that they were “confident that once all the facts and circumstances surrounding this tragic incident are brought to bear, Mr. Penny will be fully absolved of any wrongdoing.”

In the days after Mr. Neely’s killing, many city leaders, politicians and advocates for New Yorkers struggling with mental illness and homelessness had called for Mr. Penny’s immediate arrest. They said Mr. Neely’s killing highlighted the city’s failure to care for its most vulnerable and marginalized residents.

Some Democratic politicians had criticized Mayor Eric Adams for his muted initial response to the killing. Days later, on Wednesday, the mayor said in a speech that Mr. Neely’s “life mattered” and that his death was a “tragedy that never should have happened.”

In a statement on Thursday, after the district attorney’s office said it planned to charge Mr. Penny, Mr. Adams said: “I have the utmost faith in the judicial process, and now justice can move forward against Daniel Penny.”

Mr. Neely, who had been a subway performer known for his impersonation of Michael Jackson but in recent years appears to have experienced severe mental illness, had boarded a northbound F train at the Second Avenue station in the afternoon of May 1, said Juan Alberto Vazquez, a freelance journalist who recorded the video that captured what happened inside the subway car.

Mr. Vazquez recalled that Mr. Neely had said “‘I don’t mind going to jail and getting life in prison,’” and “‘I’m ready to die.’”

By the time the train stopped at Broadway-Lafayette station, where it remained, Mr. Penny had pinned Mr. Neely down on the ground in a chokehold, as two other men grabbed his arms and legs. Mr. Vazquez said he had not seen Mr. Penny grab Mr. Neely but that he had heard a thump and had then seen both men on the floor.

The police said they had received a call at 2:27 p.m. about a fight on an F train at the station.

At around 2:29 p.m. another passenger can be heard in the video saying that his wife had been in the military and knew about chokeholds, and warning the men that they should make sure Mr. Neely had not defecated on himself.

“You don’t want to catch a murder charge,” he says.

Mr. Neely was taken to Lenox Health hospital in Greenwich Village, where he was pronounced dead. Two days later, the medical examiner’s office ruled Mr. Neely’s death a homicide and said that the cause of death was compression of his neck.

As news of Mr. Penny’s upcoming charges reverberated on Thursday, Marc H. Morial, the National Urban League president and chief executive officer, said in a statement that the district attorney’s decision to charge him “reminds us that a measured response to this shocking episode was necessary.”

“While not always swift, a methodical approach to justice in this case bends towards the fair application of the rule of law,” he said.

Joshua Steinglass, a veteran homicide prosecutor who helped lead the trial team in the case against former President Donald J. Trump’s family business, is leading the investigation, according to the district attorney’s office.

Second-degree manslaughter, also known as reckless homicide, will require prosecutors to prove that Mr. Penny caused Mr. Neely’s death and did so recklessly, meaning that he knew that the chokehold could kill Mr. Neely and unreasonably chose to apply it anyway. If Mr. Penny is convicted, he could spend up to 15 years in prison.

Mr. Penny’s lawyers will most likely argue that the force he used against Mr. Neely was justified given the harm that he believed Mr. Neely represented to Mr. Penny, other passengers or both.

Prosecutors will have to prove that Mr. Penny used deadly force without having believed that Mr. Neely was also using deadly force or was about to.

Many activists and politicians had called for Mr. Penny to be charged with murder. But that was an unlikely scenario. To win a murder conviction, prosecutors would most likely have had to show that Mr. Penny had intended to cause Mr. Neely’s death or acted with “depraved indifference,” which might have been a difficult standard to meet under the circumstances.

The Manhattan district attorney office’s confirmation that it planned to charge Mr. Penny suggested that it had determined it had enough evidence to arrange his surrender. However, the office will still have to secure a grand jury indictment to proceed with a felony case against Mr. Penny, who grew up on Long Island and has no criminal record.

Nate Schweber contributed reporting.