TORONTO -- Warning: The following article contains graphic language that may be disturbing to some readers.

A vice-principal at a renowned Toronto private school told an Ontario court Friday he was able to identify a teenage boy accused of sexually assaulting two fellow students in a video of one of the incidents.

Emile John said he first saw the video of the Nov. 7, 2018, incident nearly a week after it happened, as he and other officials at St. Michael's College School tried to figure out who was involved.

John said he recognized the accused as one of the people holding down the arms of the victim, he said, while coaches with one the school's football teams later identified some players. None of them could identify the victim at the time, though they eventually learned his name from other students, he said.

The vice-principal said he struggled to watch the entire clip that day. "I had to walk away initially, because it was pretty graphic and pretty disturbing," he told the court.

The accused teen has pleaded not guilty to two counts each of gang sexual assault, sexual assault with a weapon and assault with a weapon related to two incidents in which students were sexually assaulted with a broom handle.

The incidents, which involved different complainants, took place in October and November 2018.

Taking the stand Friday, John said he and then-principal Gregory Reeves had just dealt with an incident of bullying at the school when Reeves received the video.

In the bullying case, a group of students had put another student into a sink in only his underwear, John said. That incident culminated in the expulsion of some students and a call to police on Nov. 12, 2018, he said.

He and Reeves watched the video of the sexual assault on Nov. 13, and consulted the coaches that same day, he said. They did not immediately call police, though they planned to do so eventually, instead choosing to first conduct their own investigation by interviewing some of the students involved, he said.

He acknowledged knowing about other unspecified incidents at the school, though said he was not aware of several specific occurrences named by the defence.

"There was bullying happening at St. Mike's, absolutely," he said.

Earlier Friday, one of the football coaches testified he was not aware of any incidents of violence or bullying at the school until he saw the video of the November incident.

Under cross-examination, Daniel Lumsden, who also teaches accounting at the school, denied previously hearing about or seeing a video or image of an incident in October in which a player was sexually assaulted.

He also denied allegations that he instructed students during study hall to delete that image or video from their phones.

"That's a lie," the coach said. "It never occurred, that never happened in study hall, no."

In December, court viewed two videos in which one of the complainants recounted the incidents to a police investigator.

In one video, he described being sexually assaulted with a broom handle by a group of students in the school's locker room in October 2018.

In the second recording, he recalled seeing a group sexually assault another student in a similar way the following month, also in the locker room.

The complainant did not mention the accused when discussing the October incident, but alleged the teen held back the arms of the victim in the November assault.

The teen who testified was initially one of the suspects in the November 2018 incident, but the charges against him were dropped.

Three teens have pleaded guilty to sexual assault with a weapon and assault with a weapon for their roles in the incidents and have been sentenced to two years of probation.

One of them also pleaded guilty to making child pornography for recording one of the sex assaults in a video that was then widely distributed.

Another student received a two-year probationary sentence with no jail time after pleading guilty. The charges against another student, aside from the one who testified, were withdrawn.

None of the teens involved in the case -- which includes the accused, the complainants and some of the witnesses -- can be identified because they were underage at the time.

This report by The Canadian Press was first published Jan. 29, 2021.