Gym owner and black belt Nicollas Welker Araujo has been arrested on suspicion of sex crimes against a minor, ABC News reports. Araujo, 27, is the owner of Overall Brazilian Jiu-Jitsu Academy in Agoura Hills, California, and has been head coach at the location since 2016.

According to reports Araujo was arrested after parents became concerned about inappropriate conduct, being charged on suspicion of raping “a person who is incapable of giving consent because of a developmental or physical disability,” and “lewd or lascivious acts with a child under 14.”

Araujo, a Sao Paulo native who arrived in California in 2013, is currently being held on $400,000 bail. An investigation into the charges is ongoing. Overall bills itself as Ventura County’s premiere self defense and fitness school for adults and kids.