(CNN) — The man accused of killing a woman by setting her on fire on a New York City subway car last month pleaded not guilty to murder charges Tuesday and was ordered held without bail. Sebastian Zapeta-Calil, a 33-year-old undocumented migrant from Guatemala, was previously indicted on charges of first- and second-degree murder and arson in the killing. CNN has reached out to his lawyer for comment. Police say Zapeta-Calil calmly walked up to 57-year-old Debrina Kawam on the morning of December 22, as she was sleeping on an F train approaching the Coney Island–Stillwell Avenue subway station in Brooklyn and used a lighter to ignite her clothes and the blanket that was wrapped around her. Kawam, who authorities say resided in New Jersey after a stint in New York’s shelter system, died by homicide caused by thermal injuries and smoke inhalation, according to a complaint filed in Brooklyn Criminal Court. The attack has stoked fears among New Yorkers about safety on subways and in the city at large, after several high-profile, violent incidents in recent years. During an initial court appearance in December, Zapeta-Calil claimed to have no knowledge of the incident, noting his alcohol consumption. During questioning with police, Zapeta-Calil said he sometimes drinks and loses his memory of events, waking up at home or on a train with no memory of how he got there, according to court documents. He added that he sometimes sleeps on the subway. On the morning of the incident, he said he woke up on the F train but did not remember how he arrived there, the documents show. When police presented him with video of the incident, Zapeta-Calil said, “Oh, damn, that’s me,” according to the documents. Zapeta-Calil repeatedly told police that he did not remember the incident, the documents show. “I am very sorry. I didn’t mean to. But I really don’t know. I don’t know what happened, but I’m very sorry for that woman,” Zapeta-Calil told police, according to the court documents. Surveillance video of the incident – which appeared to show Zapeta-Calil sitting on a bench across from the subway car and watching Kawan burn – played a critical role in helping police find a suspect. Hours after the attack, authorities released images from surveillance and police body cameras, and three high school students recognized the suspect and reported it to police, who found Zapeta-Calil on a subway train in Midtown Manhattan about eight hours later. He was found with a lighter in his pocket, New York City Police Department Chief of Transit Joseph Gulotta said. Zapeta-Calil was deported in 2018 and subsequently returned to the US illegally, according to federal immigration authorities. His most recent address in an arrest report was listed as a homeless shelter in Brooklyn for men struggling with substance abuse, the NYPD said. Zapeta-Calil told police that he’s lived in the US for five years and has been working as a laborer in Queens, according to court documents. “These are significant counts,” Brooklyn District Attorney Eric Gonzalez said after Zapeta-Calil was indicted. “Murder in the first degree carries the possibility of life without parole. It’s the most serious statute in New York state law and my office is very confident about the evidence in the case and to hold Zapeta accountable for his dastardly deeds.”