British citizen Jamal al-Harith stunned his Christian family when he blew himself up in a suicide bombing mission carried out in behalf of the Islamic State (ISIS) earlier this month against Iraqi forces near Mosul. Harith grew up as a Christian in Jamaica, but converted to Islam when he left his family.

Harith's name was changed to Abu-Zakariya al-Britani when he joined ISIS. 

Harith's cousin, Trevor Fiddler, told The Guardian that they never really understood Harith's conversion to Islam because they were a "normal Jamaican family" who believed in the "church of God." Initially, they believed Harith was innocent, but now they are not so sure.

"I was surprised when he went that way as the rest of us are all Christians," he said. "He was just a bit of a silly boy. There was never anything mentally wrong with him – the only thing I can think is that he was brainwashed," he said.

"We never thought he should have been in America in the first place. We all believed him and thought he was telling the truth to us. But now we think he must have been lying and must have been training the whole time for this. It was all a lie," Fiddler added.

Harith was born Ronald Fiddler in Manchester back in 1966. His parents are from Jamaica, and they are devout, churchgoing people. However, he converted to Islam in his 20s. According to his sister, he left Christianity in search of peace of mind after going through a difficult childhood. After doing so, he began to travel to Muslim countries.

Somehow, he was found by U.S. special forces in a jail in Kandahar, Afghanistan back in January 2002. Harith claimed he was an innocent victim who viewed Americans as his saviours. He was then brought to Guantanamo Bay in Cuba for further questioning. He stayed there for over two years but was later released.

Harith returned to Britain, and was paid £60,000 for a joint interview with the Mirror and ITV where he recounted his ordeal as a Guantanamo prisoner. He even made a compensation claim against the British government, which reportedly netted him up to £1m.

After a decade, Harith went back to an ISIS-controlled region in Syria in 2014. His wife, Shukee Begum, tried in vain to convince him to go home to be with their children. But he refused.

Fiddler said they could not understand Harith's actions, and they have no clue what happened to his money. "We've no idea what he did with the money – I mean most of us didn't even know about it. We think he lied and now we will have to come to terms with what he has done," he said.

Fiddler and his family might be puzzled by Harith's actions, but other converts to Islam told CNN how they were convinced by ISIS militants to join their cause.

Akram Ahmed, 22, said he was simply working in his cell phone repair shop when an ISIS member approached him to carry out a job. Ahmed admitted he felt flattered to be chosen to carry out a task for a nation ruled by the laws of Islam.

"The Caliphate persuaded us with religion. I am a student of sharia law in university. So these ideas are convincing to me," Ahmed said.

He was tasked to use his mobile phone to film key government and security buildings and find weak points that ISIS militants could exploit to enter the city. Ahmed said he regretted his actions, and it's something that would haunt him for the rest of his life.

"I hope there will still be a place for me in my community one day. Now if I walk in my street people will say I killed their children. If I go to the mosque people will say he killed my children. If I come to get married, people will say he killed our children," he said.