By Syed Shoaib Hasan
BBC News, Islamabad
News of Mohammad Naeem Noor Khan's release from custody in Pakistan has attracted a great deal of attention.
Mr Khan was arrested in the eastern city of Lahore in July 2004
But then Mr Khan was no ordinary prisoner.
At the time of his arrest three years ago, he was accused of being a key link between al-Qaeda leaders and militants.
"But now any charges against him are gone with the wind," said his lawyer, Babar Awan, after his client was released for lack of evidence.
The Pakistani president is believed to have celebrated Mr Khan's arrest
All this is a far cry from July 2004, when Mr Khan was arrested amid much fanfare and widely labelled as the "information technology chief of al-Qaeda in Pakistan".
That same description was apparently used by none other than President Pervez Musharraf in his autobiography.
While the president never used Mr Khan's name, his choice of words tally with all that is known about Mr Khan.
The book says he was born in Karachi and graduated from a local engineering university with a bachelor's degree in computer engineering.
It goes on to say he was recruited into al-Qaeda by Khalid Sheikh Mohammed, ran al-Qaeda's information technology wing after Mohammed's arrest, and was himself arrested in Lahore on 21 July, 2004.
The arrest was hailed as a "vital breakthrough in the war against terror" at the time.
And it is true to say that today, questions still remain as to what exactly were Mr Khan's connections with al-Qaeda, if indeed he had any.
Intelligence officials are in no doubt. They say that a laptop recovered from Mr Khan at the time of his arrest contained information about several terror plots.
They say it also contained details of targets such as financial buildings, railway networks and airports in the UK and US.
Along with other information gleaned from the suspect's interrogations, security agencies said it helped them foil several terror plots.
They say the information also led them to arrest several alleged al-Qaeda operatives, including Ahmed Khalfan Gailani.
Mr Gailani, chief suspect in the 1998 bombings of the US embassies in East Africa, was arrested in Gujarat in north-eastern Pakistan.
Information provided by Mr Khan also reputedly led to the arrests of 13 al-Qaeda suspects in the UK, in July 2004.
President Musharraf said in his autobiography that the arrest was one of the major hidden successes of the "war on terror".
With this background, it seemed that Mr Khan was destined to spend the rest of his life in a Pakistani or American secret prison.
At best, it seemed likely he would be sent to Guantanamo Bay.
But there has always been a cloud of controversy over his exact status.
The press has been full of conspiracy theories alleging Mr Khan's connections with foreign and domestic intelligence agencies.
Some argue al-Qaeda is no longer the force it was in Pakistan
Amid the flurry of speculation, no-one is sure where he is now.
While the news of his release was made public on Monday, he was actually freed at least a month earlier, in mid-July.
Among the various theories about his whereabouts, the most popular is that he has moved abroad.
Some analysts say that Mr Khan's release confirms that he was co-operating with Inter Services Intelligence (ISI) and was kept in custody for his own safety.
They say the old al-Qaeda network has now been all but broken in Sindh and Punjab provinces.
"In Karachi especially, the last major al-Qaeda operatives left were arrested in 2005," says an ex-intelligence official.
"In this regard many believe Mr Khan played a pivotal role.
But most analysts agree that there is now a new wave of militants, largely unknown to security agencies.
"It's a murky tale in which there are no clear answers to any of the key questions," said the official.