Footage has been posted online which appears to be of a man thought to be the first British suicide bomber in Syria posing for pictures minutes before he died.
Abdul Waheed Majeed, 41, looks relaxed as he talks to insurgents before apparently driving a lorry into a jail in Aleppo and detonating a bomb last week.
The married father of three, who was born and raised in Crawley, West Sussex, can be seen next to the vehicle packed with explosives thought to have been used in the prison break.
Officials have not confirmed the identity of the bomber amid reports that a UK jihadi, who used the name Abu Suleiman al-Britani, carried out the bombing.
But people that knew him told reporters that the man shown in the 45-minute video appeared to be Majeed.
Asked to say some words before the attack, he says: "Sorry? I can't speak. Everyone asks me that and... I'm not a very good speaker. My tongue has got like a knot in it - tell him that. Tell him it should come from the heart and I can't do it."
The "martyrdom" video was released by Jabhat al-Nusra, the al-Qaida-aligned group which is fighting against the Assad regime and more moderate opposition forces and whose black flag appears to be draped over the heavily-armoured lorry.
Shaky footage shows a large explosion at the prison's walls after several minutes of intense gunfire, the force of which is so strong it throws two cameramen filming it backwards.
Earlier, pictures emerged of Majeed looking relaxed and smiling with local children near the Turkey/Syria border.
The images were sent by Majeed from Syria to his family in the Langley Green area of Crawley.
In one picture, he is seen wearing pink Minnie Mouse-style ears while he cuddles a child. In another, he is pictured kneeling surrounded by children as they give the peace sign.
Counter-terrorism officers have searched Majeed's home in Martyrs Avenue, which is also the ex-home of schoolgirl Sarah Payne's killer Roy Whiting , a police spokeswoman said.
Majeed, known as Waheed, left Britain six months ago, telling his family he was going on a humanitarian mission to Syria, Crawley community leader Arif Syed said.
Mr Syed said Majeed would phone or Skype his family every three days, but communication was lost with him about nine days ago.
When news emerged about the suicide bombing in Syria, the family of Majeed - who is of Pakistani descent - started to panic, he added.
Majeed's uncle, Mohammad Jamil, 65, said his nephew - who is a father of two boys and a girl aged 18, 16 and 12 and husband to Tahmina, 36 - had never shown any sign of extremism.
Mr Jamil said the family would "be shocked" if official confirmation emerged that Majeed was the suicide bomber.
But this week extremist preacher Omar Bakri Mohammed told the London Evening Standard that Majeed was "a very dear brother".
He claimed Majeed had been an active student and valued member of the banned extremist Al-Muhajiroun organisation between 1996 and 2004 and had wanted to further the "Muslim cause".
Bakri said Majeed would organise his sermons in Crawley and record the lectures and distribute them.
Speaking at Broadfield Mosque in Crawley, Mr Syed said Majeed's family and the local community had no knowledge of his apparent links with Bakri.
Mr Syed said: "What Bakri is saying from Libya is all heresy. We have absolutely no knowledge whatsoever."
He added that the family had had no confirmation that Majeed was behind the attack and accused the authorities of embarking on a "witch-hunt" by raiding properties when the local Muslim community had offered full co-operation.