However, no disciplinary action will be taken against Fiona Viotti, the school said on Monday.
“As the teacher resigned from Bishops with immediate effect on the 11th October, 2019, no disciplinary action can be taken against her by the school for these breaches,” headmaster Guy Pearson said in a statement.
The 32-year-old history teacher and water polo coach, who is married, quit amid allegations of a relationship with an 18-year-old pupil on October 10.
Since then four more boys have come forward and charges of sexual misconduct, which took place between 2013 and 2019, were investigated.
Investigators, advocate Francois van Zyl and attorney Graeme Dorrington, said their findings were based on information obtained during interviews.
However, Viotti was reportedly re-admitted to a psychiatric clinic last week and not fit to be interviewed, Booth said.
The investigators found Viotti had breached the Bishops Code of Professional Conduct for Teaching Staff and the Code of Professional Ethics issued by the SA Council of Educators.
The probe could not determine to whom Viotti had allegedly sent naked selfies and a video of herself masturbating.
Pearson said the investigators would report their findings to the appropriate authorities.
“The school is co-operating with the authorities in this regard,” Pearson said.
The investigators said there was no indication that the school had any knowledge about the sexual misconduct with pupils.
Netwerk24 reported that two of the boys were in matric, one is in Grade 11, one is a student at UCT and another lives overseas and is the father of a child.