A Yorktown teacher who allegedly sent sexually explicit Internet messages to what he thought was a 15-year-old girl appeared in a federal White Plains court Monday.

According to police 34-year-old Gregg Cavaluzzi, of Yorktown, traveled to Elmsford on May 31 and expected to have a sexual rendezvous with a 15-year-old. However, the person who Cavaluzzi thought was receiving his explicit messages was actually an undercover detective, and the teacher was arrested, police say.

At Cavaluzzi's appearance in U.S. District Court Monday, his attorney, Clinton Calhoun, asked if his client could be enrolled in a drug treatment program, but prosecutors argued against it, saying Cavaluzzi is a danger to society and should stay in jail.

Cavaluzzi, a former history teacher at Pelham Middle School, was taken back to jail after the judge said he needed more time to make a decision on the drug treatment program. Cavaluzzi is due back in court Thursday.