WHITE PLAINS, N.Y. A New York City policeman and former owner of the Iron Tiger studio in West Milford has admitted in court that he brought underage girls to his home and his martial arts studio to have sex. Trent Young of Middletown, N.Y., pleaded guilty last Thursday to taking the girls, ages 14 to 16, across state lines for sex in 2003 and 2006. Young, who is 41, faces a mandatory minimum of 10 years in prison when sentenced in January in federal court in White Plains. He said he twice took girls from his home to his Iron Tiger studio for sex. In the third case, he took a girl from her Brooklyn home to his home via New Jersey. Young, who spent nine years with the NYPD, was suspended when he was arrested in 2007 and was fired upon pleading guilty. He has been in a federal prison since Jan. 7, 2008, after being arrested on Dec. 27, 2007, by Middletown, N.Y., police. Young was charged with rape after one of his young karate students came forward accusing him of the crime, according to Middletown police Lieutenant Patrick Freeman. She was 13 when the abuse began in December 2005. Within two years, it is alleged that Young had sex with the girl up to 40 times at several locations, including his home in Middletown and at his martial arts school on Cahill Cross Road. A second of Young’s students alleged similar charges after the first student came forward. Young is a married father of three children. He was a school teacher in New York City before becoming a police officer.