Updated at 3:07 p.m.: Revised throughout with new information.

A 34-year-old martial-arts instructor in McKinney is accused of sexually assaulting two of his students.

Timothy Vidal (Collin County Sheriff's Office)

McKinney and Allen police have filed sexual assault charges against Timothy Vidal, who worked at Tiger Rock Martial Arts academy in McKinney.

He turned himself in at the Collin County jail last week, Allen police Sgt. Jon Felty said. His bail is set at $225,000.

One academy employee told police Vidal had admitted to assaulting one of the students, according to an affidavit released Wednesday.

The girl in the McKinney case said the abuse started when she was 14.

She reported her allegations after she learned Vidal had been charged in Allen, where he is accused of assaulting a 16-year-old student.

The girl in the McKinney case said she had not reported the assaults before because she feared for her well-being and worried no one would believe her. She said Vidal, who has earned a sixth-degree black belt, was intimidating.

She said Vidal had assaulted her four times in recent months, including during a trip to Galveston for a martial-arts competition, according to the affidavit.

Court records show that Vidal's wife, who also worked at the martial-arts center, filed for divorce Monday.

Vidal declined a request for an interview.

The Tiger Rock Martial Arts website no longer mentions Vidal, but last year the site identified him as a master instructor.

The martial arts franchise fired Vidal on April 3, according to a written statement obtained by KXAS-TV (NBC5).

"We take this situation very seriously and are committed to providing a safe environment for all members," the statement said. "We have a NO TOLERANCE policy and took swift and immediate action upon learning of these allegations on Monday."

Anyone with information about the cases may call Allen police investigator P. Jackson at 972-633-6727.