Daniel Penny returned to a Manhattan courthouse this morning for opening statements in his manslaughter trial for the death of Jordan Neely, an erratic homeless man he placed in a chokehold during an outburst on the subway.

Outside, protesters held signs and a megaphone and blasted Penny's actions as "illegal," although his defense has argued his actions were entirely justified under the law because of threats Neely shouted out loud on the subway car.

Inside the courtroom, prosecutors delivered their remarks first, conceding that Neely "scared many of the people" on the train where he died.

"Jordan Neely took his last breaths on the dirty floor of an uptown F train – at the time he died he was 30 years old, homeless, on synthetic drugs, and suffering from mental illness," Manhattan Assistant District Attorney Dafna Yoran began. 

PROTESTERS ACCUSE MARINE VET OF WHITE SUPREMACY AS JURY SELECTION BEGINS IN SUBWAY VIGILANTE CASE

Daniel Penny arrives for opening arguments in his trial at Manhattan Criminal Court in New York City on November 1, 2024. Penny, a Marine veteran, is charged with second-degree manslaughter and criminally negligent homicide in the 2023 death of Jordan Neely on a New York City subway train. (Adam Gray for Fox News Digital)

Video of the incident shows other passengers helped Penny restrain Neely, who later died. The trial kicks off after more than a week of jury selection.

Prosecutors, in a 45-minute opening statement, said Penny maintained the chokehold for 5 minutes and 53 seconds, calling the move "unnecessarily reckless."

"He did not intent to kill him, but under the law deadly physical force such as a chokehold is permitted only when it is absolutely necessary and only for as long as it is absolutely necessary," the prosecution continued.

Screenshot from bystander video showing Jordan Neely being held in a chokehold on the New York City subway.  (Luces de Nueva York/Juan Alberto Vazquez via Storyful)

The defense countered that Penny was defending himself and other passengers from Neely's threats of violence.

"This is a case about a young man who did for others what we would want someone to do for us," the opening statement from defense co-counsel Thomas Kenniff began. "Words like ‘I’m ready to die. I'm ready to serve a life sentence,’ when these threats spoken in the confined [space] in a moving subway car, you either bury your head and pray or you stand up and protect thy neighbor. That’s what Danny Penny did."

Penny grew up in a middle-class New York family and joined the Marine Corps to serve his country and also to secure the means to pay for a college education, his lawyers said. 

He was studying architecture at the New York City College of Technology and working jobs as a swimming instructor and barback at the time of his encounter with Neely, whom lawyers described as "a seething psychotic" who was "high on drugs" when he boarded the subway car and started screaming. 

This undated photo, provided by Mills and Edwards, LLP, in New York, Friday, May 12, 2023, shows Jordan Neely, left, with Carolyn Neely, an aunt. Daniel Penny, 24, a U.S. Marine veteran who used a fatal chokehold on agitated New York City subway passenger Jordan Neely, was freed from custody hours after surrendering to face a manslaughter charge filed nearly two weeks after the encounter.  (Courtesy Mills & Edwards, LLP via AP)

"As the doors seal shut, and the train goes towards the dark tunnel, Neely slams his jacket on the ground with such force that the train falls silent," Penny's defense continued. "He demands drinks, food and money. He tells passengers that if they don’t give them what he wants, he is going to take it from them."

He raised his voice, ranting about going back to the Rikers Island jail, getting a life prison sentence and being ready to die, the defense continued.

"Passengers begin flooding towards the far end of the subway car, Neely sets his sights on a group of female passengers, [and] at that moment Danny sees a mother barricading her son behind a baby stroller," the lawyers said. "Neely utters the words, ‘I will kill,’ and, ladies and gentleman of the jury, when Jordan Neely threatened to kill there was only one thing Danny Penny could do."

Protestors, including Christopher Neely, uncle of Jordan Neely, gather calling for Justice for Jordan Neely outside of the trial of Daniel Penny at Manhattan Supreme Court in New York City on Friday, November 1, 2024. Today is the first day of opening statements in Penny’s trial, where he is charged with second-degree manslaughter and criminally negligent homicide in the 2023 death of Jordan Neely on a New York City subway train. (Adam Gray for Fox News Digital)

After Neely announced the threat, there was no time to "de-escalate the situation," they said. Penny acted defensively to take down the madman.

"Danny’s intent is not to kill Mr. Neely, in fact he did not want to hurt him at all," the defense continued. "The evidence will show that Danny made every conscious effort to avoid harm."

Penny used what the defense described as a "non-fatal chokehold" he hand been trained to use.

VETERAN IN SUBWAY VIGILANTE CASE WASN'T TOLD HE KILLED MAN THREATENING PASSENGERS DURING INTERROGATION

"His purpose in using the hold was to contain him until the police arrive – something that took longer than anyone on the train would have expected," the lawyer said.

Penny remained at the scene until police arrived. Neely was still breathing when he let him go.

After the opening statements, the first witness took the stand, an NYPD officer who responded to the scene. Neely's relatives, seated in the back of the courtroom, grew emotional during the questioning.

Neely did not have a weapon when officers arrived. They found only a muffin in his jacket pocket. Neely had a pulse but was not breathing, and officers administered the opioid antidote Narcan, but it did not revive him.

There were women and children on the train, and Penny told detectives he perceived a threat, according to testimony from pretrial hearings.

Daniel Penny arrives for opening arguments in his trial at Manhattan Supreme Court in New York City on November 1, 2024. Penny, a Marine veteran, is charged with second-degree manslaughter and criminally negligent homicide in the 2023 death of Jordan Neely on a New York City subway train. (Adam Gray for Fox News Digital)

When Neely walked into him, he said, he put him in a chokehold.

"I'm not trying to kill the guy," he told detectives. "I'm just trying to de-escalate the situation."

Penny is a 25-year-old Marine Corps veteran and college student.

Neely was a 30-year-old homeless man and former Michael Jackson impersonator with a history of mental illness and criminality, including a prior charge for assaulting a 67-year-old New York City woman in 2021.

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Penny faces up to 19 years in prison if convicted.