New Delhi, September 12: It has been 18 years since the US witnessed the unprecedented terror attacks but an intriguing question continues to linger -- how did Osama bin Laden, the chief architect of the strike, reach Abbottabad in Pakistan and live there without detection, probably for 6 years?

Abbottabad, where Laden lived with his family in a three-storey house before being hunted down and killed by the American special forces on May 1, 2011, is located just 120 kms from Pakistan's capital Islamabad and the Army Headquarters in Rawalpindi.

The house, with a big lawn, was located just about 1.5 kms away from the Pakistan Military Academy. 9/11 Attacks 18th Anniversary: From Attack on Twin Towers of World Trade Center to Pentagon, What Happened on September 11, 2001.

Still, the world's most wanted terrorist lived there undisturbed while the Americans were searching for him in the mountains of Afghanistan and carrying out unsuccessful air raids at suspected places there. And the Pakistani military was pretending to be helping out the Americans in the hunt.

Rumours were also spread, off and on, that he had either died due to some unknown illness or was killed in some US air raids.

The CIA, while keeping the Pakistanis in the dark, finally tracked him down to this house and American special forces carried out a daring midnight operation.

Under the special orders of US President Barack Obama, commandos of the US Navy SEALs dived into the compound in three helicopters and in a 40-minute operation killed Laden, along with some others there, took away his body and dumped it in a sea.

The helicopters came from a US base in Afghanistan and the operation was monitored live by Obama from White House.

Pakistan, which claimed to have no knowledge about his presence, raised a hue and cry over it being kept in the dark and violation of its "sovereignty" by the American forces.

The US intelligence tracked Laden down to the house through a courier, who used to visit the house from time to time. Since Laden never used the modern tools of communication, like phones, to avoid detection, he used to communicate with his cadres through intermediaries.

The CIA started tracking the courier from August 2010 and his visits to the house in Abbottabad led them to suspect Laden's presence there.

The US intelligence agency used satellites to get a better idea about Laden's presence but there was no conclusive evidence as the Al Qaeda chief would never come out of the building.

They then roped in a local doctor Shakil Afridi to visit the house for confirmation. He, along with some nurses, did so, pretending to be undertaking a vaccination programme. Besides, confirming Laden's presence physically, they collected blood samples for DNA matching with the terrorist's sister.

Once the presence was confirmed, Obama on April 29, 2011 authorised the raid at the compound, without informing the Pakistani establishment.

But one question still remains unanswered - how did Laden live there without being detected by the Pakistani intelligence agencies, which are supposed to be very efficient?

Or is it that he lived there with the complicity of Pakistani intelligence agencies and the military establishment?

According to some reports, the house was built in 2005 and Laden lived there for six years before he was killed.

Perhaps, the US suspected Pakistani establishment's complicity and that is why they were kept in the dark about the ‘Operation Geronimo' to hunt down the most wanted terrorist.

An agitated Pakistan lodged a protest with the US for "violating" its "sovereignty" by entering its territory without authorization and arrested the doctor who helped the CIA in tracking down of Laden.

Does it indicate that Pakistan did not want Laden to be hunted?

(The above story first appeared on LatestLY on Sep 12, 2019 04:20 PM IST. For more news and updates on politics, world, sports, entertainment and lifestyle, log on to our website latestly.com).