A Valley Stream man faces federal charges in connection with his February arrest by Nassau police for allegedly posing online as a teenage boy to meet a 14-year-old girl, authorities said Monday.

David M. Murillo, 31, was remanded pending trial after a hearing Monday in Central Islip federal district court, prosecutors said.

At the time of his Feb. 28 arrest, Murillo was serving probation on a 2006 conviction related to using internet chat rooms to seek a sexual relationship with a minor who was actually a detective posing online as a 13-year-old girl. He faces up to 50 years in prison on the latest counts, a federal complaint said.

According to the court papers, Nassau police charged Murillo after the girl’s mother turned the tables on him — posing as her 14-year-old daughter, arranging a meeting at a Hicksville mall, and contacting authorities.

Details of the charges were offered by a Nassau County police detective — who is also an FBI task force officer — in the complaint against Murillo filed March 27 in U.S. District Court.

Murillo’s attorney, Stuart Austin of Garden City, was not immediately available for comment on Monday.

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John Marzulli, a spokesman for the U.S. Attorney’s Eastern District, said in a telephone interview Monday that federal prosecutors added the new charges against Murillo because “his alleged conduct is a federal crime.”

Murillo used the name “Dave Michaels” while posing as a high school junior to communicate with the girl through social media, including Instagram and Snapchat, the complaint said, and the girl informed him she was 14.

After the girl’s mother saw sexually explicit cellphone texts between her daughter and Murillo, she assumed the teenager’s identity and set up a face-to-face meeting with him at the Broadway Mall, according to the complaint.

When Murillo arrived at the mall to meet who he expected was the girl, he met her mother instead, the complaint said. Murillo identified himself as “Dave,” according to the complaint, and the girl’s mother called Nassau police. A responding officer found several images of child pornography on Murillo’s iPod Touch and took him into custody, the complaint said. Authorities did not say why Murillo remained at the scene after the woman contacted police.

Murillo “enticed and coerced” the victim to take sexually explicit photographs of herself and send them to him from her smartphone, according to the complaint. He also sent similar pictures to her and pretended to be 17 years old, the complaint said. Some of the images as well as videos seized depicted “sexually explicit conduct by minors, including minors that appear to me to be as young as five years old,” the FBI and Nassau police said in the complaint.

Murillo faces federal charges of enticing a minor to create child pornography and possession of child pornography.

In February, Nassau police charged Murillo with five felony counts of possessing a sexual performance by a child and one misdemeanor count of endangering the welfare of a child. Bail was set at $265,000.

A spokesman for the Nassau County District Attorney Madeline Singas said prosecutors in her office are consulting with federal officials to determine what charges, if any, Murillo will face in state court.

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“A final determination has not yet been reached,” Singas spokesman Brendan Brosh said.