A FEW days after the murder in December 2007 of Benazir Bhutto, a two-time former Pakistani prime minister, the country's then president, Pervez Musharraf, held a press conference in high spirits. Cracking jokes about his country's famed unruliness, the then dictator dismissed concerns about a hapless police effort to secure evidence and investigate the killing. He suggested Ms Bhutto was partly to blame for having disregarded security warnings. But on Thursday April 15th a high-powered UN report into Ms Bhutto's death took a more critical view of these events. For Mr Musharraf, now living in exile in London, and the Pakistani military establishment he once led, its conclusions should be devastating.

The report finds Mr Musharraf's government guilty of an “inexcusable” failure to provide proper security to Ms Bhutto, who was campaigning for elections at the time of her murder. “Ms Bhutto's assassination,” it says, “could have been prevented if adequate security measures had been taken.”

Worse for Mr Musharraf and the army, the 65-page report accuses his government and its agents of a “deliberate” effort to cover up the circumstances of Ms Bhutto's murder—including hosing down the crime scene less than two hours after the attack and ensuring no post mortem was carried out on Ms Bhutto's body. It also finds that Pakistan's intelligence agencies, including the main army-controlled Inter-Services Intelligence (ISI), “severely hampered” investigations into the crime.

The report accuses Saud Aziz, police chief of Rawalpindi, the garrison city where Ms Bhutto was killed, of deliberately preventing investigators from reaching the crime scene for nearly two days. He also ordered the hosing of the crime scene—after receiving a call, the report says, from Pakistan's army headquarters. The report calls an official enquiry into this damning event a “whitewash”. “Hosing down the crime scene so soon after the blast goes beyond mere incompetence,” the report says. “It is up to the relevant authorities to determine whether this amounts to criminal responsibility.”

Dispelling a popular Pakistani conspiracy theory, one of the report's authors, Heraldo Muñoz Valenzuela, a Chilean diplomat, said there was no evidence to suggest Ms Bhutto's widower, President Asif Zardari, was involved in her killing. Yet the report offered encouragement to other conspiracy theories: “While [Ms Bhutto] died when a fifteen-and-a-half-year-old suicide bomber detonated his explosives near her vehicle, no one believes that this boy acted alone.” The report casts doubt on the official Pakistani conclusion—supported by American and British spies and detectives—that Baitullah Mehsud, then head of Pakistan's Taliban militants, was behind the killing. “It remains the responsibility of the Pakistani authorities to carry out a serious, credible criminal investigation that determines who conceived, ordered and executed this heinous crime of historic proportions.”

To be fair to Mr Musharraf, some of the bungling described in the report is unremarkable in Pakistan. For example, it notes that police deployed on rooftops around the site of Ms Bhutto's last rally were supposed to have binoculars, but did not. To some extent, the unhelpful role of the country's intelligence agencies might also be less sinister than it appears. In a country with a history of army intrigue and interventions, civilian officials are often paralysed by uncertainty over their generals' wishes. This might explain some of the shoddy policing—with officials reluctant to investigate Ms Bhutto's killing in case the ISI had a hand in it.

At best, then, the report highlights the debilitating effect on Pakistan's institutions of its periodic spells of military rule. It also suggests the contempt the country's uniformed leaders display towards their civilian counterparts. Yet this is clearly not all. The report, which was kept under wraps for two weeks at the timorous request of Mr Zardari's government, raises serious questions about the role in the killing played by Mr Musharraf's regime, which included Pakistan's current army chief, General Ashfaq Kayani, who led the ISI until shortly before Ms Bhutto's murder. Whether these mysteries will be solved is another matter—in a country where political murders rarely are.