New York City police were working Monday to identify the woman who died after being intentionally set on fire inside a stationary subway train as well as more information about a man, now in police custody, who is a “person of interest” in the crime.

Chief of Transit Joseph Gulotta said Sunday that questions about the suspect’s background and whether the victim was homeless were all part of an active police investigation.

Transit police apprehended the man, who has not yet been publicly identified, after receiving a report from three high school students who had recognized the man. They had seen images of the suspect taken from surveillance and police body cam video and widely distributed by police.

“New Yorkers came through again,” said New York City Police Commissioner Jessica Tisch on Sunday. She described the case as “one of the most depraved crimes one person could possibly commit against another human being.”

Tisch said the suspect and the woman had been riding a subway train without any interaction between them to the end of the line in Brooklyn at around 7:30 a.m. on Sunday.

After the train came to a stop, surveillance video from the subway car showed the man “calmly” walk up to the victim, who was seated motionless, possibly sleeping, and set her clothing on fire with what appeared to be a lighter. The woman’s clothing then “became fully engulfed in a matter of seconds,” Tisch said.

Police do not believe the two knew one another.

Officers on a routine patrol at the Coney Island-Stillwell Avenue subway station smelled and saw smoke and discovered the woman on fire, standing in the middle of the subway car. After the fire was extinguished, emergency medical personnel declared the woman dead at the scene.

Unbeknownst to the officers, the suspect had remained at the scene and was seated on a bench on the subway platform, just outside the train car, Tisch said. Body cameras worn by the officers caught a “very clear, detailed look” at the suspect and those images were publicly disseminated.

After later receiving a 911 call from the teenagers, other transit officers identified the man on another subway train and radioed ahead to the next station, where more officers kept the train doors closed, searched each car and ultimately apprehended him without incident, Gulotta said. The man had a lighter in his pocket when he was taken into custody, Tisch said.

In a statement, Brooklyn District Attorney Eric Gonzalez said “The depravity of this horrific crime is beyond comprehension, and my office is committed to bringing the perpetrator to justice.”

“This gruesome and senseless act of violence against a vulnerable woman will be met with the most serious consequences,” he said.

The case marked the second fatality on a New York subway Sunday.

At 12:35 a.m., police responded to an emergency call for an assault in progress at the 61st Street-Woodside Station in Queens and found a 37-year-old man with a stab wound to his torso and a 26-year-old man with multiple slashes throughout his body. The older man was pronounced dead at a nearby hospital while the younger man was in stable condition, police said.

An investigation was continuing.

New York Gov. Kathy Hochul this year has sent New York National Guard members to the city’s subway system to help police conduct random searches of riders’ bags for weapons following a series of high-profile crimes on city trains. Hochul recently deployed additional members to help patrol during the holiday season.

About a year ago, Hochul supported funding to install video cameras on every train car in the New York subway system, said Michael Kemper, chief security officer for the Metropolitan Transportation Authority. He and other officials on Sunday credited the cameras with helping to track down the suspect so quickly.