It has been little more than a week since the world was shocked, and my life shattered, by the death of my beloved wife, Mohtarma Benazir Bhutto. Benazir was willing to lay down her life for what she believed in – for the future of a democratic, moderate, progressive Pakistan. She was willing to stand up to both dictators and fanatics, those who would distort and defy our constitution and those who would defame the Muslim Holy Book by violence and terrorism. For me and my children, our pain is unimaginable. But I feel even sorrier for a world that will have to move forward without this extraordinary bridge between cultures, religions and traditions. My wife was truly unique.
I married Benazir in 1987, and spent less than five years living with her in the Prime Minister's house over her two terms in office, interrupted by military interventions. I also spent more than 11 years as a prisoner in Pakistani jails without a conviction on charges that former Prime Minister Nawaz Sharif and General Pervez Musharraf (who brought and pursued the charges) have now publicly acknowledged were politically motivated. Even before Benazir was elected Prime Minister in 1988, the intelligence agencies of Pakistan began a campaign to discredit her, targeting me as her husband and several of her friends. The term "Mr Ten Percent" was attached to my name as an appendage by public relations hired guns working for the intelligence agencies, just as the names of her friends abroad were besmirched by ridiculous charges that they headed the non-existent "Indo-Zionist" lobby.

This campaign of character assassination was possibly the first institutional application of the politics of personal destruction. She was the target, and her husband and friends were the instruments. The purpose was to weaken the case for democratic government in Pakistan. It is perhaps easier to block the path of democracy by discrediting democratic politicians.

During the years of Benazir's governments, she was constrained by a hostile establishment, an interventionist military leadership, a treacherous intelligence network, a fragile coalition government and a presidential sword of Damocles constantly threatening to dismiss Parliament. Despite this she was able to introduce a free media, make Pakistan one of the 10 emerging capital markets in the world, build thousands of new schools, electrify many villages, and change the lives of women in Pakistan, as well as draw attention to the cause of women's rights in the Islamic world.

Her murder does not end her vision. Her assassination must not be allowed to empower her assassins. Those responsible must be held accountable. I call on the United Nations to commence a thorough international investigation of the circumstances, facts and cover-up of my wife's murder, modelled after the ongoing investigation into the assassination of Lebanese Prime Minister Rafik Hariri. And I call on the friends of democracy in the West to endorse the call for such an investigation. An investigation under the control of the government of Pakistan – such as the Scotland Yard one – will have no credibility. One does not put the fox in charge of the hen house.

But it is also time to look forward. In profound sadness, the torch of leadership in the Pakistan Peoples Party (PPP) has been passed to a new generation of leadership, to our son Bilawal Bhutto Zardari. I will work with him and support him, and to the extent possible, protect him. The Bhutto family has given more than anyone can imagine to the service of our nation, and in these difficult days it is critical that the party remains unified and focused. Benazir, always prescient and wise, understood that. Knowing that the future was unpredictable, she recommended that the family keep the party together, for the sake of Pakistan. And this is what we aim to do.

The Musharraf regime has called off the elections set for 8 January, not because of any logistical problems as they claim, but because General Musharraf and his "King's Party" know for certain that they would be thoroughly rejected at the polls, and that the PPP and other pro-democracy parties would win a two-thirds majority.

Elections have been postponed to 18 February. Democracy in Pakistan can be saved, and extremism and fanaticism contained, only if these elections are free, fair and credible. To that end the people of Pakistan must be guaranteed elections: 1) conducted under a new, neutral caretaker government not composed of cronies of General Musharraf's party; 2) supervised by a truly independent and autonomous election commission formed in consultation with the major political parties of Pakistan; 3) monitored by trained international observers with unfettered access to all polling stations and with the right to conduct exit polling to verify results; and 4) arbitrated by an independent judiciary as provided in the constitution of Pakistan. In addition, there must be a restoration of full electronic and print press freedoms, and all political activists, lawyers and judges in detention must be released.
The enemies of democracy and tolerance who took my wife from me must be exposed and marginalised. Dictatorship and fanaticism have always been rejected by the people of Pakistan and in a free and fair election will be defeated again. And on that day, the vision and indefatigable spirit of Benazir Bhutto will burn brightly, and in the words of John F Kennedy's inaugural address, "the glow from that fire can truly light the world".

Asif Ali Zardari, a former Pakistani senator, is the co-chairman of the Pakistan Peoples Party and the husband of the late Benazir Bhutto