Shahid Mohammed, 32, was detained 50 miles from the Pakistani capital of Islamabad in connection with the fatal fire in Birkby, Huddersfield, in May 2002, it emerged today.
Five children and three adults from the Chisti family died in the firebomb attack on the house, with one man later convicted of murder and two others of manslaughter.
Mohammed, who has been on the run since being arrested by West Yorkshire Police and skipping bail, has been the subject of a huge manhunt for 12 years.
He was arrested by police in Pakistan in the early hours of January 22 after a long investigation and police say court proceedings “are now underway to return him to the UK to face charges”.
But the remaining members of the Chisti family, who still live on the same street where the fatal fire took place, are preparing for a potentially long, drawn-out process as Pakistan has no extradition treaty with the UK.
This does not stop the UK from requesting the extradition, but it means the case and the length of time it takes is now a matter for the Pakistani authorities.
Muhammad Shafique, who escaped the fire that killed eight of his relatives, said: “We are pleased with the news. It has been a long time coming but finally he has been arrested and is in custody.
“It is great news for the family. There are still a few hurdles to cross but it is positive news and we are happy about it.
“There is no extradition treaty and there is no precedent before this, so we don’t know how long it can take. However the evidence that they have asked for in the Pakistani courts, they have been supplied with that.
“However, I am sure they will give a chance to the suspect to defend himself and we don’t know how long it can take.
“We are prepared for that. We know there could be hurdles and the judicial process could take some time over there.
“An important thing is that he is in custody, even if it takes months he is not out enjoying a normal life. He is in custody and will have to spend his time there.
“If it does take months or years, he will be in custody during that time, which is not quite like prison but he is not enjoying a normal life.
“We have been sentenced to life without our loved ones, he will hopefully realise what it is like to be living without family and loved ones.”
He added: “I would like to take this opportunity to thank the police, they have continued with this investigation and their perseverance finally paid off.”
Joseph Kotrie-Monson, an extradition lawyer at criminal defence firm Mary Monson Solicitors’ Manchester office, says arrangements for incoming extradition to the UK from Pakistan do exist, but are rarely used.
He said: “There has been no extradition treaty with Pakistan in living memory, despite gestures at negotiation on the issue over the last 20 years or so.
“But government between the two countries can extradite when they really want to, even without a treaty. Negotiation between the governments of two countries without a treaty over a one-off extradition are called ‘ad-hoc’ agreements.
“These are very rare, and have been used to extradite alleged criminals from Pakistan to the UK but not, to my knowledge, the other way round.
“The Pakistan court when the person is arrested will demand to be satisfied by the UK government that there is a case to answer before allowing extradition back to the UK, but this is a fairly low threshold, compared to the ‘beyond reasonable doubt’ that a British jury would require at trial before saying someone was guilty.”
Kirklees councillor Mehboob Khan, who has been in regular contact with surviving family members Abdul Chisti and Mr Shafique, said: “We are all delighted with the news that the 12-year manhunt has finally come to an end.
“We are still anxious that the extradition process runs smoothly. This is because there is no extradition agreement between Pakistan and Great Britain and there may well be pitfalls along the way.
“Because of the prominence of this case in Great Britain the authorities in Pakistan are going to co-operate.
“The federal police are dealing with it so it is not down to provincial police, which has been a problem in the past because they have not been as effective in searching for this person.
“We are grateful to West Yorkshire Police for not giving up on this and putting in substantial effort to track down this individual.
“We hope things will run smoothly but you can never tell, these matters can take months or even years to come to a conclusion. We will continue to put pressure on authorities to make sure this case remains a priority for them.
“We waited 12 years and if it means having to wait longer it is something they are willing to do.”
The attack in 2002 saw the killers pour petrol through the letterbox and put a petrol bomb through the window of the Chisti family’s home.
The fire killed Nafeesa Aziz, 35, and her daughters Tayyaba Bootall, three, Rabiah Bootall, 10, Ateeqa Nawaz, five, Aneesa Nawaz, two, and Najeebah Nawaz, six months.
Miss Aziz’s brother, Mohammed Ateeq-ur-Rehman, 18, also died in the fire, and their mother, Zaib-un-Nisa, 54, died a week later in hospital.
In July 2003, three Huddersfield men - Shaied Iqbal, Shakiel Shazad Amir and Nazar Hussain - were convicted for their part in the crime.
Police said Mohammed’s re-arrest came after close work between authorities in the UK and those abroad and they are working on bringing him back to this country.
Detective Superintendent Lisa Griffin, of West Yorkshire Police, said: “We have informed members of the Chisti family of the latest development in the case, and will continue to keep them informed throughout.
“Operation Elvington has clearly been a major and long-running inquiry and I thank residents who have come forward with information over the years for their support.
“We remain utterly focused on working with the UK Foreign Office and authorities in the nation in which the 32-year-old is currently being held to bring him back to the UK to be put before a court.”