By Mark Daly
BBC Scotland's investigations correspondent
The terror cell which attacked Glasgow Airport was the first of its kind in the UK.
Its members were young, well-educated professionals, with an ability to blend in seamlessly.
A doctor with a UK passport, Bilal Abdulla, and Cambridge educated Kafeel Ahmed were able to infiltrate the very fabric of Scottish society.
On Tuesday, Abdulla was found guilty of conspiracy to murder and faces life in prison.
His co-conspirator, Ahmed, escaped that fate, dying from 90% burns sustained during the attack. He had no intention of going to prison. This was to be a suicide mission.
Kafeel Ahmed died four weeks after the failed attack on Glasgow Airport
In his will, which he sent to his brother Sabeel just hours before the attack on Glasgow Airport, he said: "If they can't figure out who it was, keep me alive for as long as possible.
"If I am caught, then try to maintain calmness - spare me from their dreaded prisons."
I wanted to know what could have driven this promising young man to give his life in such a way.
Kafeel Ahmed was born in Bangalore, India, on 17 January 1979.
His parents were both doctors and devout Muslims. His father Maqbool, was a member of the fundamentalist missionary sect, Jamaat-e-islami.
He had a younger brother Sabeel, to whom he was extremely close, and a sister.
As a toddler, Ahmed's family moved to Saudi Arabia where they lived until he was a teenager.
It was during this time he learned about the plight of Muslims around the world, in particular the ethnic cleansing of Bosnian Muslims. This was to stay with him his whole life.
He was a particularly bright student. A distinction holder and diligent worker, he was awarded a degree in mechanical engineering at the BDT College of Engineering in Davangere.
From there he moved to Belfast for a masters degree in aeronautical engineering at Queens University and was heavily involved in the university's Islamic society.
He moved to Cambridge in 2004, where he stayed at the Islamic Academy and studied for a PhD in computational fluid dynamics at Anglia Ruskin University.
Bilal Abdulla (pictured) met Kafeel Ahmed at Anglia Ruskin University
It was here he was to meet Bilal Abdulla and his co-defendant Mohammed Asha - who was found not guilty. He would form a close bond with Abdulla.
Ahmed returned to Bangalore in 2005 after his mother fell ill. He was a pious Muslim before he went to the UK, but on his return, those who knew him noticed he had changed.
I travelled to Bangalore. Some people who knew him told me how they could not accept that he was the man in the photos and suggested it was a western plot to sully the name of Islam.
But some, including his local Sunni priest, told me about how Kafeel Ahmed had changed when he returned from the UK.
Imam Mohammed Hassaan said: "After he came back from London his clothes changed, his manner of speaking also changed.
"One day he came to the mosque and after he offered his prayers we told him that you are offering your prayers while wearing shorts, this is not right.
"To this he replied that you don't have enough knowledge about these matters, saying that he knew more than we did.
"His father heard this and said - 'Son, this is not right, you have changed. Your behaviour is not right.' So we had this debate and since then we have not talked to each other."
Whilst Ahmed's radicalisation was cemented in Cambridge, it had its roots in India.
Behind the country's burgeoning economy, there lies a bloody Islamist struggle which has cost hundreds of lives.
Praveen Swami is deputy editor with the New Delhi bureau of Frontline and is considered one of India's foremost experts of Islamist terrorism.
Praveen Swami said feelings of oppression had fuelled Islamism
He told me about the resentment felt by many young Indian Muslims.
"There's a deep feeling of oppression and the assumption all these years was that somehow economic progress and education would slowly wipe away these resentments and grievance," he said.
"That hasn't happened. If you look at most Islamist cells found in this county, the leadership is upper middle class, middle class certainly, people with a high degree of good education skills - a new generation of Muslims who ought to be benefiting from India's newly growing economy.
"But these kids encounter fearsome kinds of discrimination from day one. Delhi for example for all practical purposes is an apartheid city. In many neighbourhoods it would be almost impossible for a Muslim to get housing.
"What many of these first generation successful Muslims find is that you've done everything you needed to do to unlock the gates of the earthly paradise, and find you still can't. And maybe you start looking for another worldly paradise at that point."
I went to meet Kafeel Ahmed's family. They were of course reluctant to talk to a western journalist.
His mother Zakia, spoke out at the time of the Glasgow attacks when she told the world's media that she did not accept that it had been her son who crashed the jeep into the airport.
But it was true. It was her son. And she stopped speaking to the press.
Almost 18 months later, I arrive unannounced at their home yet was welcomed like a long-lost friend.
Dr Zakia Ahmed and her husband Maqbool are now retired doctors and live in the mainly Muslim area of Banashankari in Bangalore.
I also met Sabeel, Kafeel Ahmed's brother. He is also a doctor and was working in Liverpool on June 30th 2007, when he received a text directing him to an email account belonging to Kafeel.
In it, was Kafeel's will, and details of his "secret project". Sabeel was arrested a few hours after reading it.
He told me that he knew nothing of Kafeel's plans, but admits that when he read the will - an hour after the airport attack - he was caught between loyalty to his brother and utter confusion.
Sabeel pleaded guilty to withholding information - not passing on details of the will to police - and was sentenced to 18 months in a UK prison in May 2008.
He had already served half of that when he was deported back to India.
I wanted to know what could have sent Kafeel Ahmed on his path to jihad.
Both brothers were fundamental Muslims. But Kafeel Ahmed was prepared to take things a stage further and tried to kill hundreds of innocent people.
He was acutely aware of the plight of Muslims across the world. He collected material about the atrocities of Bosnia and Chechnya and, in February 2006, organised a presentation about it in Bangalore.
His mother Zakia, attended that, and offered me an insight into what could have driven her son to give up his life in the name of jihad.
Zakia Ahmed said her son had been "very caring" as a child
In a filmed interview, she said: "He gathered the people, he distributed the pamphlets, he arranged a big meeting, then he spoke regarding Chechnya - and then he said 'why the Muslims are suppressed everywhere. I want to bring awareness to the people'. So he did.
"He has seen many things, in his childhood. We heard a lot about Bosnia. That also was in his mind most probably, so he had seen, right from his childhood, Muslims were suppressed everywhere."
She told me about the son she once knew. How, as a two-year-old, he insisted on helping his heavily pregnant mother with her shopping.
"He was always very helpful. Very caring. But he's a very strong-minded person. Whatever he'll decide, he'll do it. That is his nature."
She fought back tears as she explained how she would have liked to be able to keep watch over her children 24 hours a day, but that it was "impossible for mothers to do that".
She told me how he had called her just hours before the attack but only spoke of his "secret project" and had insisted he was in Iceland.
After the Glasgow attack, the anti-terrorist branch contacted their counterparts in Bangalore and asked them to carry out a thorough investigation into Kafeel Ahmed's background.
Such is the sensitivity of the case, the Indian police still refuse to discuss it on the record, but they were prepared to give me a briefing.
They recovered the hard drive from Ahmed's computer from his home in Bangalore. They told me that it contained masses of jihadi material. This included:
- the beheadings of western hostages, including Daniel Pearl and Ken Bigley;
- lectures from Osama bin Laden; and
- the downloaded teachings of Abu Musab al-Suri - the man who has been described as the principal architect of al-Qaeda's post 9-11 structure and strategy.
I went to Norway to meet the world's foremost expert on Al-Suri at the Norwegian Defence Research Establishment.
The followers of Al Suri - or "The Syrian" as he is known - have posted his work on the internet.
It offers a practical guide to would-be Al-Qaeda jihadis and sleeper terrorist cells on how to operate.
He teaches how to self contained, to be independent of any external chain of command, and above all, undetectable.
Dr Brynjar Lia said: "He would like individuals to join forces with their closest friends, people they trust the most, and keep to a very small and secretive group and not tell anyone else about this group.
"Then (they) start obtaining training on their own, finding financing on their own, accessing the kind of material they can, via the internet, and start operating on their own.
"(This is) based on the general guidelines that have been presented and outlined and detailed in the literature that the jihadi movement has put out on the internet. This is the core model for the decentralised part of the movement."
Dr Lia said the key to Al-Suri's methods, is to be creative with materials close at hand - that way, the cells can stay anonymous longer.
He added: "They used whatever they could get their hands on and they didn't have many contacts outside their own cell.
"They were not detected and they were not on the radar of the police before they carried out the attacks. All these factors suggest that they followed the model of al-Suri."
Al-Suri, who lived in London for three years during the 1990s and was Osama Bin Laden's mouthpiece, was captured by the CIA around two years ago. It is not known where he is held.
BBC reporter Mark Daly's film, "Inside Scotland's Terror Cell", will be broadcast on BBC One Scotland on Tuesday, 16 December, at 2235 GMT.