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23 June 2014, 17:42 | Updated: 30 March 2016, 13:50
The dad of a man from Cardiff who features in video for a group of Islamic extremists says he's changed completely.
Ahmed has told Capital he was shocked to see his son - 20 year old Nasser Muthana - in the footage for the militant group ISIS, asking muslims here to join rebels abroad.
He said: "100% different. It's like he's turned 180 degrees.
"Nasser is not like this, he never harmed anybody, he never shout at me or his mum or his big brother. He was always a lovely boy, I miss him and I love him.
"I do confirm he is my son but the way he talks there has to be someone there writing for him to read behind the screen or someone forced him to say this.
"You have a house full of kids and someone has disappeared from it. It's like being a single parent."
Nasser and Aseel Muthana both attended the Al Manar centre in Cathays.
Officials there deny being part in any radicalisation and say they're concerned about the role of the internet in grooming young extremists.
Ahmed hasn't spoken to Nasser since November when he left Cardiff.
His dad later found out he'd crossed over the border from Turkey to Syria.
He said there was no sign that he had become radicalised: "He wasn't talking to me about fighting, about killing. If I saw it on television he'd say 'don't watch it' and then he turned himself into one of them.
"It's devastating for me and for the people of Cardiff too".
Nasser's brother - 17 year old Aseel - is also thought to have travelled to Syria.
A second man from Cardiff - 20 year old Reyaad Khan - also appears in the ISIS video.
His mum who wanted to remain anonymous said: "There is someone behind them, teaching these young innocent boys, brainwashing them into thinking they're going to help people.
"There's someone behind them and we don't know who."
There are now calls for the muslim community and the authorities to work more closely to try and deal with the threat of young people being radicalised.
David Cameron says work is ongoing to track - and try and stop - grassroots extremism.