The British-educated Muslim man now believed to be the notorious Islamic State killer "Jihadi John" reportedly took anger management classes as a student.
A teacher at Mohammed Emwazi's high school told the BBC he used to get into fights as a teenager and had difficulty keeping his emotions in check.
"We would find that he would get very angry and worked up and it would take him a long time to calm himself down," the teacher said, speaking on condition of anonymity for security sake, according to the BBC. "We did a lot of work as a school to help him with his anger and to control his emotions and it seemed to work."
Emwazi is now believed to be the black-clad masked militant pictured in the beheading videos of a number of Islamic State hostages, including American journalists James Foley and Steven Sotloff.
Jihadi John came to symbolize the brutality of the Islamic State after repeatedly appearing in the videos waving a knife with a serrated edge in one hand while standing beside his victims and menacingly taunting Western governments with a strong London accent.
Emwazi's former teacher expressed disbelief that the teenage boy she knew who displayed "a lot of respect" for the help he received during his time at Quintin Kynaston school in northwest London could have gone on to commit such acts of barbarity.
"I remember him achieving great things that he never thought he was capable of," she told the BBC, and he was "very, very pleased with going to university and doing well."
At the time she felt that he was one of the school's success stories and believes he came from a supportive, loving family who, if he is Jihadi John, he has let down immeasurably.
"He had every chance of doing well," she said. "I just can't believe he would do that."
Officers from MI5, Britain's domestic security agency, have reportedly questioned teachers at the school, hoping they may offer up some hints as to when he first might have started expressing sympathies with radical Islamic ideology.
Emwazi's former friends are also struggling to come to terms with reports that the person they once hung out with allowed his life take such a radical trajectory, and are offering up a multitude of motives.
One former classmate phoned a popular London talk radio show to say he remembered Emwazi hitting his head on a metal goal post in the playground while trying to run from some boys spoiling for a fight.
The caller said Emwazi was about 10 years old at the time and "he was not the same ever since that brain injury."
Another friend told reporters that the Kuwaiti-born son of a taxi driver and stay-at-home mom may have become radicalized during his school days by meeting Mohammed Sakr, who was reportedly later killed by a U.S. drone strike in Somalia.
A former schoolfriend told Britain's Telegraph newspaper that Emwazi was always hanging out with Sakr's younger brother and they may have developed radical views at the mosque.
Other old acquaintances cited his time at the University of Westminster where he completed a computer science degree and developed closer associations with Islamic radicals, according to reports.
It is clear that by the time he completed his degree in 2009, he was already on MI5's radar.
When he attempted to travel to Tanzania with two friends after graduation he was stopped, questioned and sent back home because authorities believed his real intention was to travel to Somalia to join the militant group Shabab.
In the ensuing years he was also blocked from returning to Kuwait, where he said he had a job and fiancee, and intelligence officers repeatedly tried to coerce him into becoming an informant.
By 2011, Emwazi was allegedly part of a radical group known as the North London Boys which was sending money, equipment and fighters to help Shabab, according to court documents obtained by the BBC.
Another man linked to the group is Lebanese-born Londoner Bilal Berjawi, who joined Shabab in Somalia and was killed in a drone strike in 2012.
The Muslim advocacy group CAGE is adamant that Emwazi was radicalized because of this repeated harassment by the security services. The group claims their actions prevented him from living a normal life in London, and instead made him feel as if he was living under constant surveillance.
Those claims have been dismissed as "reprehensible" by 10 Downing Street.
And on Friday, Prime Minister David Cameron vehemently defended the job that British security services were doing in keeping the country safe.
Emwazi's family has not returned to their home, in a rapidly gentrifying area of northwest London, since news reports first linked him to Jihadi John on Thursday.
One of his sisters is reportedly "devastated," and told a friend that family members "are having to move, to change their identities," according to Britain's Daily Mail.
The neighborhood where Emwazi once lived was quiet on Saturday, with residents privately going about their business.
Many did not want to discuss publicly how the community was dealing with the news reports. However, at a nearby mosque that serves the Bengali community, the imam said he has lived in the area for 19 years and has never experienced something like this.
"Everybody is talking about it," Moulana Abdul Mukith said. "Everyone is saying why? Why did this boy go to Syria?"
He denied any suggestions the community was divided or hostile toward other faiths.
"The population is not fighting, everybody is one nation in a place," he said. "Christians, Jewish, Hindus, Muslims, every religious person is united here."
Boyle is a special correspondent.