George Mason High School’s boys tennis coach Rafael “Rally” Diokno was arrested Monday after an investigation determined he had a sexual relationship with a student, according to authorities.

Fairfax County police said that Diokno, 29, of Falls Church, is facing three felony charges of taking indecent liberties of a child by a custodian for his role in the relationship. He is currently being held without bond at the county’s Adult Detention Center.

An investigation that started on June 16 found that Diokno’s unlawful conduct began in May and took place at various locations around Fairfax County. Falls Church City Public Schools said that it immediately contacted F.C. City Police and Child Protective Services upon receiving an allegation of inappropriate conduct toward a student-athlete on June 3.

The school system said that Diokno, who was hired only to coach tennis at Mason and was not a member of FCCPS’ faculty, was fired on June 4. Diokno did not have access to the school or its students as a result of his termination, per FCCPS.

Falls Church schools will not be commenting on personnel matters or the cases specifics while the investigation is active.

It also said it is aware that there may be other potential victims and, in a statement, added that “It is crucial that individuals feel comfortable and supported in coming forward if they have additional information or concerns.”

Diokno was hired in February 2016. While he was not a full-time employee of the school system, FCCPS said that all procedures were followed during his onboarding. That included fingerprinting and background checks with the Federal Bureau of Investigation, the Virginia State Police, Child Protective Services, and reference checks.