Federal prosecutors say a New York man demanded $12,000 from his niece’s father to stop the 13-year-old’s forced marriage to a man in Yemen.

Yousef Goba appeared briefly in Brooklyn federal court Tuesday ahead of his extradition to Buffalo, New York. A U.S. citizen, he moved to Yemen in July 2013. His sister, also a U.S. citizen, and her five children moved there from Buffalo later that year. The kids’ father stayed in the U.S. to work, a common practice in Yemeni-American families. Goba’s sister and her children planned to return in the summer of 2014. But they never got on the plane, because prosecutors say Goba would not let her 13-year-old daughter leave.

Instead, on April 4, 2015, Goba’s brother-in-law walked into a Buffalo FBI office and told agents that one of his kids was being held hostage in Yemen: Goba was threatening to marry her off to an adult unless he paid thousands of dollars.

When the little girl’s family first arrived in Yemen, they lived with family in a small village, before moving to Sana’a to experience city life. About a year after they arrived, the mother tried to take her children to her father’s house in Al Jawf but Goba wouldn’t let the 13-year-old girl leave, according to the complaint. The mother eventually left with her other four children, leaving the girl behind with Goba.

At that point, Goba barred his niece from talking to her father in the U.S., according to the complaint. He demanded the father pay him $3,000, then $12,000, for her freedom.

If the money didn’t arrive, Goba allegedly told the dad, he’d marry the girl off to another brother-in-law from a poor village. He taunted the dad with “pictures of the Victim Child pointing at a wedding cake, a picture of the Victim Child’s hand with a ring on it, a picture of a wedding cake, and a picture of the proposed groom sitting next to a wedding cake,” the complaint says.

Goba allegedly also told the father that he’d found an imam to perform the marriage ceremony—and that he’d forge the dad’s signature to make the marriage stick.

“Neither the Victim Father nor the Victim Mother consent to the Victim Child getting married at such a young age,” the complaint says. “Both parents agree that when the Victim Child is 18 years old, she can decide whether or not she wants to marry.”

On April 3, 2015, Goba texted the dad on WhatsApp that men were offering him money for the wedding. Just before 11 p.m., Goba allegedly followed up, saying that a man had offered him as much as he wanted for the young bride.

The father accused Goba of “selling a child.”

The next day, the dad asked the FBI for help.

On April 9, the dad spoke to Goba on a call recorded by the FBI. He asked how much he’d have to pony up to get his daughter back. Goba told him that the girl was engaged. (The girl’s father did not respond to a request for comment.)

“The Victim Father told Goba that a 13-year-old child cannot get engaged. The Victim Father told GOBA that marrying a 13-year-old girl is illegal religiously and by law,” the complaint states. “The Victim Father told Goba that he is not allowed to marry off his 13-year-old daughter and described the act as ‘rape.’”

He demanded his daughter’s return and Goba allegedly demanded $11,000. It’s not clear if it was ever paid out. But the girl did not come home.

By the following year, the girl’s mother had remarried to a Yemeni national and was living in a war-torn region. The girl’s father travelled from the U.S. to Yemen to move his other four children to a safer area, to live with his family. By then, the victim child had been married off, living with her husband in Qoaz, “a very small village.” He told feds that the ongoing war in Yemen makes travel to Qoaz to retrieve his daughter too unsafe for him to undertake.

An arrest warrant for Goba was issued when the dad got back from Yemen. But he wasn’t apprehended until June 2, when he got off his plane in New York. His brother Yahya Goba pleaded guilty to terrorism charges in 2003.