A Teaneck middle school teacher is behind bars Friday after a former student accused him of sexual assault.

Authorities say James Darden, an eighth-grade teacher at Thomas Jefferson Middle School, had a sexual relationship for three years with one of his students. The alleged relationship began in 1999 when the victim was 13 years old.

The victim, now 21, came forward in April with the allegations. Authorities say the alleged sexual encounters took place inside the school, including the dean?s office.

?These acts are alleged to have occurred on the premise of the Thomas Jefferson Middle School, in the classroom, the men?s faculty bathroom and at the defendant?s home in Plainfield,? Bergen County Assistant Prosecutor Liliana Siebi.

The victim also told authorities she and Darden would have explicit conversations and video exchanges over the Internet.

Darden is being held on $500,000 bail on charges of aggravated sexual assault, endangering the welfare of a child and official misconduct.