NEW YORK — A suspect has implicated himself in the death of a man who was pushed onto the tracks and photographed just before a train struck him, authorities said Wednesday, and the captured image set off an ethical debate after it appeared on the front page of the New York Post.

The suspect was taken into custody Tuesday after investigators recovered security video that showed a man fitting his description working with street vendors near Rockefeller Center, said New York Police Department spokesman Paul Browne. The suspect made statements that indicated he was involved in Ki-Suck Han's death, Browne said.

Police didn't release his name, and no charges were immediately announced. He was still being questioned Wednesday.

Witnesses told investigators they saw the suspect talking to himself Monday afternoon before he approached the 58-year-old Han of Queens at the Times Square station, got into an altercation with him and pushed him into the train's path.

The Post published a photo on its front page Tuesday of Han with his head turned toward the train, his arms reaching up but unable to climb off the tracks in time. It was shot by freelance photographer R. Umar Abbasi, who was waiting to catch a train.

Abbasi told NBC's "Today" show Wednesday that he was trying to alert the motorman to what was going on by flashing his camera.

He said he was shocked that people nearer to the victim didn't try to help in the 22 seconds before the train struck.

"It took me a second to figure out what was happening ... I saw the lights in the distance. My mind was to alert the train," Abbasi said.

"The people who were standing close to him ... they could have moved and grabbed him and pulled him up. No one made an effort," he added.

Trains generally arrive at the stations going 25 mph, but it's not clear how fast the train was going when it struck Han. The waiting area is a narrower than other subway stations, but the platform is still about a dozen feet wide.

In a written account Abbasi gave the Post, he said a crowd gathered taking videos and snapping photos on their cellphones after Han was pulled, limp, onto the platform. He said he shoved them back as a doctor and another man tried to resuscitate the victim, but it was no use. The man died in front of Abbasi's eyes.

"I can't let the armchair critics bother me. They were not there. They have no idea what they would have done," he wrote.

Ethical and emotional questions arose over the published photograph of the helpless man standing before the oncoming train accompanied by the headline that read in part: "This man is about to die."

The moral issue among professional photojournalists in such situations is "to document or to assist," said Kenny Irby, an expert in the ethics of visual journalism at the Poynter Institute, a Florida-based nonprofit journalism school.

John Long, the ethics chairman of the National Press Photographer's Association, said in an online statement that he could not judge the photographer's actions.

"The photographer is getting all the attention because he put himself into the story by making photographs and thereby calling attention to his presence at the scene," he wrote.

Photographers often capture images that unsettle, he wrote, using as an example the iconic photo of a starving girl stalked by a vulture in Somalia or The Associated Press image of a woman burned with napalm. Choosing to publish the images is a separate issue.

"If the public needs this information in order to make informed choices for society, then we must run the photo. This is why we ran the photos of bodies floating in the streets after Katrina," he said.

He said personally, he didn't see the social value in the subway shot, but "the Post has traditionally had a higher tolerance on taste issues than most papers."

Abbasi said he didn't control how the images were used in the Post, but he did tell the "Today" show he has sold the images.

The Post declined to share the photo with The Associated Press for distribution.

Mayor Michael Bloomberg said Tuesday that it appeared the suspect in Han's death had "a psychiatric problem."

The mayor said Han, "if I understand it, tried to break up a fight or something and paid for it with his life."

Associated Press writers Tom Hays and Tom McElroy contributed to this story.