In fresh revelations about the journey from normality to infamy of the man known as “Jihadi John”, it has come to light that Mohammed Emwazi, the Briton identified as an Islamic State (IS) executioner, was once a star salesman for a Kuwaiti IT company.

Emwazi, the Kuwaiti-born but London-raised graduate who features in IS videos apparently beheading hostages in the Syrian desert, was quiet and rather withdrawn but had a natural gift for his work, a former boss in Kuwait City told the Guardian.

“He was the best employee we ever had,” the former boss said of the then 21-year-old.

“He was very good with people, calm and decent, he came to our door and gave us his CV.”

He said the staff was surprised that a Londoner would want to come and work in Kuwait, as many of his peers in the region would be looking to make the journey in the opposite direction.

The former boss added that, after a stellar probation period, the Briton disappeared completely in April 2010 after a trip to London.

“How could someone as calm and quiet as him become like the man who we saw on the news? It’s just not logical that he could be this guy.”

During his brief stint at the IT company, he twice requested emergency family leave to return to Britain. In simple English handwriting, he wrote ‘London’ as a destination for a seven-day stint on January 10, 2010.

His second request was made days before he left for good on April 25 that year. “We never saw him again,” said his employer. “But he did send us back his SIM card in the post.”

Soon after his return to London, counter-terrorism officials detained him and prevented him from returning to Kuwait.

Asked to reflect on how the young sales representative who persuaded people to buy their IT products became one of the world’s most wanted men, the employer said, “I have no answers for this. He wasn’t sociable. He was always earnest. He didn’t smile. But he wasn’t bad.

“We have Indian Christians working at this company who have been here for 17 years,” he said. “They are treated the same as everyone. You must deal with people well. You must not use force. Maybe he fell into the wrong hands when he went back.”

Asked to send a message to his former protege, the employer said, “I would say to him one thing: ‘Fear God, because Islam prohibits what you do’”

‘A hardworking student’

The former school principal of Mohammed Emwazi says he was a relatively hardworking student who showed no signs of radicalization.

Jo Shuter, former head teacher at Quintin Kynaston school in London, told BBC Radio on Monday that he was a “hardworking and aspirational young man” when she knew him.

She said he had “adolescent issues” and was occasionally bullied by other students.

Ms. Shuter said Emwazi did well enough in school to allow him to gain admission to the university that was his first choice. He earned a degree in computer science at the University of Westminster.

The former principal said neither he nor other students showed signs of embracing radical causes while at school.