More than three days after a woman was fatally burned by another passenger inside a subway train on Coney Island, officials have not yet been able to confirm her identity.

The police have charged a man, Sebastian Zapeta-Calil, 33, with murder in the Sunday morning attack. They believe he set the woman’s clothing on fire while she was sleeping on the train and she died from the burns and smoke inhalation, in a gruesome incident caught on cellphone video.

The struggle to identify the woman, whom the authorities believe was homeless, underscores how difficult it can be to gather information about people who may not have permanent addresses or personal documents. But in this case, there is an added complication: The horrific way the woman was attacked may be making her identification even harder.

“It just adds another level to a tragedy,” said David Giffen, the executive director of the Coalition for the Homeless. “A this point, we still don’t even know who she was and she can’t be mourned.”

The medical examiner’s office confirmed on Wednesday that the woman had not yet been identified and that the investigation was continuing. The Brooklyn district attorney’s office, which is investigating the case, did not immediately respond to requests for comment on Wednesday.

Joseph Giacalone, a retired New York police sergeant and an adjunct professor at John Jay College of Criminal Justice, said that burns can make simple methods of identification — using facial features, or fingerprints — difficult or impossible. That means investigators have to rely on dental and DNA analysis, or see if the victim had any surgeries that match known medical records.