A 28-year-old Vaughan woman has been charged with sexual assault following allegations that a female high school teacher was involved in a sexual relationship with a male student.

York Regional Police said the investigation began after they received information that a supply teacher for the York Catholic District School Board was involved in a sexual relationship with a male teenaged student between October and December 2017.

Police say the woman has been an occasional high school supply teacher with the YCDSB since 2014.

“These allegations are certainly upsetting for YCDSB,” said board spokesperson Sonia Gallo in an email to the Star. “We take very seriously our responsibility to ensure a safe and respectful working and learning environment for all our students and staff.”

Gallo said the woman was immediately removed from her teaching assignment position, and is on paid leave.

“This is an active investigation and we are co-operating with the York Regional Police,” Gallo wrote. “We cannot comment on the case at this time.”

Gallo said staff from the school board’s psychology department and chaplaincy team are available to provide support to staff and students.

Adriano Volpentesta, who says he’s a friend of the woman charged, said he attended Holy Cross with the 28-year-old, calling her “very caring”.

“I’m very shocked to hear that,” he said, explaining that he knew at one point she taught at St. Jean de Brebeuf Catholic High School, in Woodbridge. “She’s a very good person . . . .A nice young lady.”

Police charged Marianna Riossi, 28, of Vaughan with three counts of sexual assault and three counts of sexual exploitation.

Riossi is scheduled to appear in court in Newmarket on March 6.

With files from Jeremy Grimaldi, Vaughan Citizen