Commuters, meanwhile, absorbed the news of the second fatal subway shove in the city this month.
"It's just a really sad commentary on the world and on human beings, period," said Howard Roth, who takes the subway daily. He said the deadly push was food for thought about subway safety, "but I guess the best thing is what they tell you—don't stand near the edge, and keep your eyes open."
The suspect in Thursday night's killing had been following the man closely on a Queens platform and mumbling to herself, witnesses told police. She got up from a nearby bench and shoved the man, who was standing with his back to her, as the train pulled into the platform. He was pinned under the train as it pulled to a stop, police said.
It did not appear the man noticed her before he was shoved onto the tracks, police said, adding that the condition of the man's body was making it difficult to identify him. The woman was described as Hispanic, in her 20s, heavyset and about 5-foot-5, wearing a blue, white and gray ski jacket and Nike sneakers with gray on top and red on the bottom.
It was unclear whether the man and the woman knew each other. And it's also unclear whether anyone tried to help the man up before he was struck—or whether there was enough time for anyone to do anything.
The surveillance video was taken at a nearby intersection. It shows a woman dashing from a crosswalk and down a sidewalk.
Asked about the episode at the station on Queens Boulevard in the Sunnyside neighborhood, Mayor Michael Bloomberg pointed Friday to legal and policy changes that led to the release of many mentally ill people from psychiatric institutions from the 1960s through 1990s.
"The courts or the law have changed and said, no, you can't do that unless they're a danger to society; our laws protect you. That's fair enough," Bloomberg said on "The John Gambling Show with Mayor Mike" on WOR-AM.
On Dec. 3, 58-year-old Ki-Suck Han was pushed in front of a train in Times Square. Apparently no other passenger tried to help Han.
A photograph of him on the tracks a split second before he was killed was published on the front of the New York Post the next day, causing an uproar and debate over whether the photographer, who had been waiting for a train, should have tried to help him and whether the newspaper should have run the image.
A homeless man, 30-year-old Naeem Davis, was charged with murder in Han's death and was ordered held without bail. He has pleaded not guilty and has said that Han was the aggressor and had attacked him first. The two men hadn't met before.
Being pushed onto the train tracks is a silent fear for many of the commuters who ride the city's subway a total of more than 5.2 million times on an average weekday, but deaths are rare.
Among the more high-profile cases was the January 1999 death of aspiring screenwriter Kendra Webdale, who was shoved by a former mental patient. After that, the state Legislature passed Kendra's Law, which lets mental health authorities supervise patients who live outside institutions to make sure they are taking their medications and aren't threats to safety.
Like many subway riders, Micah Siegel follows her own set of safety precautions during her daily commute: stand against a wall or pillar to keep someone from coming up behind you, watch out when navigating a crowded or narrow platform to avoid being knocked —even accidentally—onto the tracks.
"I do try to be aware of what's around me and who's around me, especially as a young woman," Siegel, a 21-year-old college student, said as she waited at Pennsylvania Station on Friday.
So does Roth, who's 60.
"It sounds a little wimpy if you're like, 'Who's going to push me?' But it's better to be safe than sorry," he said.