Analysis: Another killing that will never be credibly solved

When a different suicide bomb attack came close to taking her life in October, Benazir Bhutto blamed both extremists opposed to democracy and rogue elements within the government of President Pervez Musharraf.

She also demanded a full investigation and appealed for the government to seek international expertise in tracing those responsible for the blast that killed 130 people when she returned from exile to Karachi.

"The attack was on what I represent," she told the media the day after at her house in the Clifton district of the city, defiant, yet clearly shaken. "The attack was on democracy and the very unity and integrity of Pakistan. [Those who died] made the ultimate sacrifice for the cause of democracy and the fundamental rights of the people of Pakistan."

Yet for all the promises by the government in the aftermath of the attack that no stone would be left unturned, 10 weeks later the authorities appear no closer to identifying which individuals or groups were responsible for what happened. There has been plenty of speculation and conspiracy, ranging from the obvious to the seemingly unlikely, and yet the government's inquiry has so far come up with nothing.

There was no claim of responsibility for yesterday's attack on Ms Bhutto and it is likely, though not certain, that, just as with the blast in Karachi, none will be forthcoming. Indeed, in the aftermath of October's blast, Baitullah Mehsud, a pro-Taliban millitant who had reportedly threatened to attack Ms Bhutto's homecoming, denied he or his supporters were involved.

In the absence of reliable facts, Pakistan's major political players and their supporters were left to level various accusations. In a nationally televised address, Mr Musharraf blamed Islamic terrorists for the killing, saying: "This is the work of those terrorists with whom we are engaged in war. Today, after this tragic incident, I want to express my firm resolve. We will not rest until we eliminate these terrorists and root them out."

But already, some of Ms Bhutto's supporters directed the blame towards Mr Musharraf. Outside the hospital in Rawalpindi to which she had been taken, supporters of her Pakistan's People Party (PPP) smashed glass doors and threw stones at cars as they chanted slogans against the President, accusing him of, at the very least, complicity in the attack.

Nawaz Sharif, another former prime minister who is now the leading opposition politician in Pakistan, vowed that no one should make political capital from his sometime rival's death. He said his Pakistan Muslim League Party would boycott the elections next month. "I think nobody stands to gain and nobody should be looking for any gains," he told the BBC. "It's a very serious situation for the country today."

Should some official version of events be provided by the government, few in Pakistan will believe it. In a country which has experienced military coups, the suspicious death of one of its military leaders and the execution of another president and in which both the military and the shadowy intelligence services retain the dominant influence, people will be ready to believe any manner of fanciful ideas about who was behind Ms Bhutto's death. Pakistan is, after all, the place where conspiracies are played out all too often.

It was the same in Karachi. Two days after the attack in October, I had lunch with a group of Pakistani journalists of whom only one was prepared to accept that Islamic extremists were responsible.

At least one blamed the military and another blamed Ms Bhutto herself, suggesting that the attack was launched with her knowledge to build political support for the political campaign she was about to begin.