For almost 10 hours on October 18, the people of Karachi choked the streets, cheering Pakistan People's Party (PPP) leader and former prime minister Benazir Bhutto in a mass catharsis on her return home from exile. As Benazir's cavalcade threaded through an enraptured throng towards the mausoleum of Mohammed Ali Jinnah where she was to address a public rally, the PPP leader stood atop an especially fortified, bullet-proof truck, waving lustily at her followers and occasionally wiping eyes brimming with tears of joy. At 12.09 am on October 19, the cavalcade had reached the Karsaz Bridge, still 10 km away from the destination. But Benazir was not to be seen—19 minutes earlier she had gone down to use the makeshift washroom built in the lower deck of the truck.

It was then that someone tossed a grenade on the right side of Benazir's truck, hoping the explosion would break the three rings of security cordon around it. The outer ring was of Pakistani policemen, the other two of the Janisar Force of the PPP. Her personal guards valiantly held their ground. In the ensuing confusion, a suicide bomber tried to sneak under Benazir's truck from the left to inflict maximum damage. Challenged, he detonated himself. (Subsequently, the truck's windshield was found riddled with bullets, suggesting a sniper had tried to ensure nobody could escape to safety.) The carnivalesque mood soon turned funereal—human flesh and limbs flew around, people wailed in agony and grief, and the death toll reached a chilling 143.

What saved Benazir was that she wasn't atop the truck at that fatal moment; the explosion was powerful enough to rip off a door of her truck. Government sources say the assassination plan reveals prior knowledge of the security architecture around Benazir. Not only was the attack three-pronged, those who masterminded it also chose a suicide bomber in order to evade the jamming devices fitted into two vehicles immediately in front and behind Benazir's truck. The jammers could have prevented any explosion triggered by a remote-controlled device, as had happened during one of the two attempts on Pakistan President General Pervez Musharraf's life in 2003.

The nature of explosives used is another indicator of intricate planning. Investigators say the suicide bomber (whose head has been recovered, and is supposed to be a 21-year-old who had a 48-hour stubble) had strapped himself with 15-20 kg of an explosive mix of C4 and Trinitrotoluene or TNT. The C4 explosive is rated as the best quality military plastic explosive that detonates with tremendous velocity, and isn't readily available. The other ingredient—TNT—has the capacity to shatter concrete structures and hillocks. Investigators say the TNT was meant to pierce through the bullet-proof casing of Benazir's vehicle, with the C4 inflicting damage over a wide area. Fortunately for Benazir, two police jeeps accompanying her bore the brunt of the explosion.

So, who were these people who could access such devastating and rare explosives, and who were aware of the obstacles they would encounter in targeting Benazir? The signature of Al Qaeda, as well as local militant groups affiliated to it, is writ large—the self-destructing agent, the total apathy towards popular sentiment, the appetite for the 'big' hit. But did these groups have the assistance, or tacit approval, of jehadi-minded elements in the administration? Benazir herself thought so. On October 19, she disclosed that she had written a confidential letter to Musharraf on October 16, informing him about three senior officials who were planning to assassinate her when she returned home.Her information, she said, had come from a brotherly country (read Afghanistan) who told her about four suicide squads having entered Karachi to kill her. "However, I had made it clear (to Musharraf) that I won't blame Taliban or Al Qaeda if I am attacked, but I will name the three officials as I know quite well my enemies in the Pakistani military and intelligence establishment," she told journalists.

Benazir has not yet named the three persons, but PPP insiders disclosed their identity to Outlook. It's an illustrious list: Brig (retd) Ejaz Hussain Shah, DG, Intelligence Bureau; Chaudhry Pervaiz Elahi, chief minister of Punjab; and Hassan Waseem Afzal, a former official of the National Accountability Bureau (NAB). A fourth, familiar name pops up in the concluding part of the letter—that of former isi chief, Lt Gen Hameed Gul, who's a vocal supporter of the Taliban and Al Qaeda.

PPP insiders believe the quartet's motive in organising the assassination attempt on Benazir was to check the burgeoning moderate political alliance between her and Musharraf. As such, the Musharraf camp was bitterly divided over his deal with Benazir. One group led by the secretary of the National Security Council, Tariq Aziz Warraich, was in favour of Musharraf sharing power with the PPP. Shah's group opposed the deal with Benazir, believing it would be at the cost of the ruling Pakistan Muslim League (Qaid-e-Azam). Ejaz Shah is close to the powerful Chaudhry brothers—Elahi and Shujaat Hussain—whose party the ruling PML-Q is, besides sharing their fundamentalist worldview.

Indeed, it was Shah who had 'arranged' the surrender of Sheikh Ahmed Omar Saeed, the killer of American journalist Daniel Pearl, on February 5, 2005, in Lahore. Then, Shah was the home secretary of Punjab. Shah knows Omar's family well as both of them belong to the Nankana Sahib area of Punjab. The relationship between Shah and Omar was really one of a handler and his agent. In an interview with Daily Times, August 13, 2007, Benazir Bhutto said, "Brig Shah and the isi recruited Omar Sheikh, who killed Danny Pearl. So I would feel very uncomfortable to have the Intelligence Bureau, which has more than 1,00,000 people under it, run by a man who worked so closely with militants and extremists."

Links with militants apart, Shah was instrumental, say PPP insiders, in splitting PML (Nawaz) and weaning away 20 PPP members in the National Assembly, to form the PML-Q. It's Shah on whom the PML-Q depends to manipulate the impending general election to its advantage. For the Chaudhry brothers, the general election is a do-or-die battle: a defeat could well spell political oblivion for them.

The third person named in Benazir's letter, Hassan Waseem Afzal, is currently secretary to the governor of Punjab. He was appointed to this post after he was removed as NAB's deputy chairman on Benazir's insistence a few months before her Abu Dhabi meeting with Musharraf in July this year. It was one step Benazir had wanted Musharraf to take as a confidence-building measure with her. Afzal had incurred her wrath because he had made it his personal mission to pursue corruption cases against her in the United Kingdom, Spain and Switzerland. It was on his order that the Interpol issued a red alert notice against her.

The fourth conspirator PPP names is Gul, a retired, dyed-in-the-wool Pakistani general who headed the isi following the jehad against the Soviets in Afghanistan and was responsible for fomenting the Kashmir insurgency in 1989. Gul worked in tandem with the Americans against the Soviet occupation of Afghanistan, but began to oppose America post-9/11. In 2003, Gul declared, "God will destroy America."

Government sources, however, say a high-level meeting presided over by Musharraf dismissed Benazir's accusations as "childish". They also say her insistence on implicating Musharraf's close associates in the Karachi carnage could even threaten her equation with the president. (The FIR filed by Benazir in Karachi states as suspects "those whose names were given to Gen Musharraf".) They claim the suicide attack bore the signature of Al Qaeda, arguing that she has incurred its wrath because of her support for military operation against the Red Mosque fanatics in Islamabad in July and for declaring that she would allow the International Atomic Energy Agency to question Dr Abdul Qadeer Khan about his nuclear proliferation activities. Her emergence as an ally of Musharraf, government sources say, explains the fury of militants who had targeted him as well earlier.

But, are Benazir's claims as ridiculous as government sources are making them out to be? Why, even Musharraf in his book, In the Line of Fire, wrote that militants roped in Pakistani air force personnel in the conspiracy to kill him in 2003. In another abortive attempt the same year, Musharraf implicated personnel of the Special Services Group charged with vip security. What was accepted as true in Musharraf's case cannot prime facie be falsified in Benazir's. Nothing is impossible in Pakistan's cloak-and-dagger politics.