There was enough time for straphangers to save the woman killed by a subway train while retrieving her gym bag, an investigator told The New York Post.

But the fast-charging No. 6 train — and the woman's panicked behavior on the track bed — was too overwhelming for the crowd of people who watched in horror Thursday as the locomotive barreled down, said the source.

"It happens. They probably didn't want to get dragged under," the source said of the witnesses not leaping to her aid.

Rose Mary Mankos first froze in place before desperately trying to get to safety. The witnesses furiously shouted to her to lie on the tracks so the train would pass safely overhead.

But she instead tried to get back out of the track bed — and then futilely tried to sidestep the train by pressing up against the platform.

Mankos, a lawyer who lived in Stuyvesant Town, was crushed to death at about 3:45 p.m. at the 77th Street station.

The LeSportsac bag she died for contained only keys, a cellphone, gym clothes and deodorant, sources said.

As investigators probed the tragic scene yesterday, friends and family recalled the New Jersey native who lived alone and once worked as a state lawyer.

"She was a quiet person, her work was excellent, she was respected and well liked," said Elise Geltzer, a spokesperson for the Department of Legal Services at the New York State Office of General Services, where Mankos worked for eight or nine years before leaving three years ago.

Mankos was more recently battling personal problems, according to a Stuy Town neighbor.

"She definitely was not 100 percent there," said Rich Pinto, 41, who said he saw her walking around the stairways and lobby of their building muttering to herself in a strange way.

"It was undecipherable muttering," he said, adding that she looked "distressed."

"I never got the idea that she was threatening, just not 100 percent there," he said.

Mankos' father, Robert, said he did not speak to his daughter often and that he did not know if she had any mental problems.

"I don't know why she jumped," he said. "I wish I could answer that. She didn't talk to me about any of her problems. I wouldn't know. She lives in New York. She has her own life. I didn't see her too often."

The North Bergen, NJ, man said he was so grief-stricken by the gruesome tragedy that he couldn't claim her body. Instead, he had his son, who lives in Pittsburgh, perform the sad task.

"I'm in shock right now. This is too hard," he said. "I'm praying, but tomorrow will be like today and the day after.

"This is not easy to get over. It's going to take a long time."

The loss hit the family even harder because Rose Mankos' mother is suffering from a severe chronic illness and is in a nursing home, according to neighbors.

"I'm 82 years old. I felt like 60 and now I feel like 105," Robert Mankos said. "It takes a lot of strength to overcome this, and strength is something I don't have right now."