The man charged with murder and arson in the killing of a woman inside a subway car in Coney Island was arraigned on Tuesday and ordered to be held in custody.

The authorities said the man, Sebastian Zapeta-Calil, lit a homeless woman on fire inside a parked F train on Sunday and then watched from a nearby bench as flames consumed her. The police have not identified the woman, but a complaint lodged in Brooklyn criminal court indicated that she died of “thermal injuries and smoke inhalation.”

Mr. Zapeta-Calil, 33, is expected to plead not guilty when he is arraigned on a formal indictment in the coming weeks, a spokesman for the Brooklyn district attorney’s office said. The shocking, apparently random attack has shaken New Yorkers and contributed to persistent worries about safety in the city’s public transit system.

Here is what we know about what unfolded on the F train:

Who is the man charged with murder?

Sebastian Zapeta-Calil is an undocumented immigrant from Guatemala who was deported in 2018 and returned illegally to the United States after that, according to federal immigration officials. It remains unclear when and where he entered the country. His last known address was listed as a Brooklyn homeless shelter for men with substance abuse and mental health problems.

He was charged on Monday with first-degree murder and arson. His lawyer, Andrew Friedman, did not immediately respond to a request for comment.

Immigration and Customs Enforcement officials said that the agency’s Enforcement and Removal Operations unit would file an immigration detainer for Mr. Zapeta-Calil with New York authorities. The detainer is a notice that immigration officers intend to take a person into custody if he is released by local law enforcement.