Born in Australia to a Fijian father and Cambodian mother, Neil Prakash travelled to Cambodia for the first time in 2012, at the age of 20. It was a confusing trip for a young man already uncertain in his faith, the BBC reported.
What he saw of Buddhism in Cambodia "didn't make any sense", he said later, in a slick recruitment video for Islamic State in Iraq and Syria (ISIS).
In the 12-minute video, which emerged online in April last year, Prakash recounts his conversion to Islam and his journey to Syria.
He explains that he was born into a Buddhist family, The Age reported in April last year.
He began questioning his faith during the Cambodia trip, where he saw people worshipping statues in Buddhist temples.
"I literally saw what 'shirk' was," he recalls in the video. "I saw people praying, crying to statues, giving money to statues.
"I asked my mother on Cambodian New Year, 'Why do I have to ask the statue if I can eat food?' It never made any sense to me."
On his return to Melbourne, he reached out to a Muslim friend and said he received an invitation to join Islam.
He was later asked to take the shahada (a Muslim profession of faith) on the last Friday of Ramadan.
"It was one of the best feelings I've had in my life, the unity that I felt with the brothers at the masjid (mosque) and how everyone looked like they were following the 'sunnah' (prophetic traditions) with the beard... and everything," he says.
It is thought he was radicalised at Melbourne's Al-Furqan Islamic Centre and bookshop.
By 2013, he found he was not satisfied with simply practising his new religion in Melbourne and wanted more.
"I thought to myself, 'What am I doing? I have a job, I have an income, a car, a house - what sacrifice have I made? What have I done for the sake of Allah?'
"All those nights I slept in comfort, I thought about the people overseas in the Muslim lands who are suffering.
"And this is when my journey really started beginning. I started attending this masjid... learning about the basics of Islam."
He sold all his possessions and left to join ISIS in Syria as a Muslim of less than two years. He rapidly rose through the ranks to become a leading recruiter.