LIVERMORE — A Judo instructor is heading to New York City to face allegations that he sexually assaulted one of his female students there.

Ryan Rebmann, 29, of Livermore waived extradition Wednesday in an Alameda County Superior Court in Pleasanton. He is now in the custody of the New York Police Department.

Livermore police learned about the alleged assault last month and began an investigation as did NYPD. The girl told investigators that she was sodomized in March while staying in a New York City hotel with Rebmann, her instructor and chaperone, and two other teenagers.

The incident, she told investigators, occurred while everyone was asleep, said Livermore Police Lt. Matt Sarsfield. The group was in New York for the night for a layover for their flight to the Dominican Republic where the group was heading to participate in a competition.

The girl reported the incident after she returned, Sarsfield said.

Based on the information detectives received, a New York magistrate issued a warrant for Rebmann's arrest on the charge of forcible sodomy. He was arrested by Livermore and New York detectives on Wednesday in Livermore.

Investigators believe Rebmann, an instructor at Amador Judo and Jujitsu Studio on Rincon Avenue, may have spoken to other people and students about the alleged assault. Detectives say they are also concerned that he may have assaulted other children or former students. He had taught at the studio for some time, Sarsfield said.

Livermore police are asking parents of children who had any contact with Rebmann to talk to their children about the nature of their interactions with him. Police ask anyone with information about this incident or any other pertinent information to call Livermore police Lt. Matt Sarsfield at 925-371-4730.

Reach Sophia Kazmi at 925-847-2122 or skazmi@bayareanewsgroup.com.