Two medics who met the Islamic State militant known as Jihadi John in Syria have described him as a quiet man hiding an adrenaline junkie streak and a "gung ho" attitude.
The British men were working at a hospital in Syria near the Turkish border when they came across the militant - named today as London man Mohammed Emwazi - as he visited friends who were injured and sick.
A man who wore full combat gear at all times, even in safe areas during the full heat of summer, he earned his high-ranking position through his aggressive behaviour.
He was, they said, a man with "nothing to lose", and who was "always ready for war".
Speaking on condition of anonymity, the men told ITV News they had previously known of Emwazi in London but never met until they came across him separately during stints in the war-torn country in 2013, some months before he became known as Jihadi John for his role in a series of videos showing the killing of hostages.
The medics said at the time they met Emwazi in Syria, he was unmarried and was a fighter with the al Nusra Front. He later switched allegiance to Islamic State.
They said he was "caring" towards his friends in hospital, bringing fizzy drinks, Haribo sweets and ice cream for them - contrasting sharply with the expensive gun and extra rounds he carried into the health centre.
Emwazi had a strong dislike of Britain, they said, and scowled when the country was mentioned. He would only admit to being "kind of" British when asked, and usually identified as Yemeni-Kuwaiti, speaking Arabic as a first language.
They also revealed Emwazi was known in Syria by his Islamic name, Abu Muharib al-Yemeni - a sign of his rejection of his British roots.
He was evasive and avoided questions about where he had come from, growing suspicious of the medics' questions before starting to quiz them instead.
The men said they were "shocked" when they found out for certain that Emwazi was indeed the militant who had become known as Jihadi John, saying they had not anticipated he could be so brutal.
One of the medics said while he was aware of Emwazi's disregard for his own safety, their experience of him visiting friends in hospital had not led them to believe beheading aid workers or anyone else would be something he was capable of.
They have since spoken to UK police about their experiences in Syria.
ITV News has been unable to independently verify their claims.
ITV News UK Editor Rohit Kachroo reports: