ISSAQUAH, Wash. -- A track coach at an eastside high school has been charged with sexual misconduct with a minor, reported KIRO 7 Eyewitness News.

Nicholas Short, 23, was an assistant track coach at Issaquah High School. Short is accused of having sex with a 17-year-old student in April.

The school district said Short, who graduated from Issaquah High School in 2003, became a paid assistant coach last spring.

Court documents said other coaches warned him repeatedly about inappropriate behavior with student athletes.

Documents said that on April 3 he was warned after he was found sitting under a blanket with a 17-year-old in the stands.

On April 6, Short was reprimanded by school officials for having dinner with some athletes and also on April 21 when he spent a track meet watching a teenage girl and sitting with the girl and her parents instead of coaching, court documents said.

Detectives said that same night, April 21, Short had sex with a student in a car at Tibbet’s Valley Park.

A police report said that two days after the alleged sex took place, the teen's parents called the school with concerns about the coach.

When interviewed by police, investigators said Short admitted he'd had sex with the teen. The Issaquah School district fired him immediately.

Short has pleaded not guilty to the charges.

The school district issued a statement concerning the allegations that read, “From the first indication there might be an inappropriate relationship here, everyone worked together to get to the truth of the situation and protect student safety.”