A spokeswoman for Merrill Lynch & Company, where she told people she worked at the time of the terror attack, said the company had no record of employing a Tania Head.

And few people, it seems, who embraced the gripping immediacy and pain of her account ever asked the name of the man whose ring she had returned, or that of the hospital where she was treated, or the identities of the people she met with in the south tower on the morning of 9/11.

“She never shared those details, and it was nothing we wanted to probe,” said Alison Crowther, the mother of Welles Remy Crowther, a man who died on 9/11 and who is credited with rescuing a number of people from the south tower, including, by Ms. Head’s account, Ms. Head. “I felt it was too private and painful for her.”

In recent weeks, The New York Times sought to interview Ms. Head about her experiences on 9/11 because she had, in other settings, presented a poignant account of survival and loss. But she canceled three scheduled interviews, citing her privacy and emotional turmoil, and declined to provide details to corroborate her story. During a telephone conversation on Tuesday, she would not explain her reticence, saying only that she had not filed any claims with the federal Victim Compensation Fund. “I have done nothing illegal,” Ms. Head said.

She has retained a lawyer, Stephanie Furgang Adwar, to represent her. Also on Tuesday, in response to a question about the accuracy of Ms. Head’s account, Ms. Adwar said in an e-mail message, “With regard to the veracity of my client’s story, neither my client, nor I, have any comment.”

No one has suggested that Ms. Head did anything to profit financially from her position as an officer with the Survivors’ Network, the nonprofit group for which she helped to raise money. But the organizations with which she has been affiliated have also questioned her account after learning of the inquiries from The Times.

For several weeks, colleagues who said they respected the good work she had done as a fixture in the survivor community have pressed her to come forward with clarifying details. But they said that they had been unable to persuade her or, in other cases, that she made representations that contradicted previous versions she had given.