KARACHI, Pakistan - The senior detective leading the investigation into the suicide attack on Benazir Bhutto withdrew from the case after the opposition leader accused him of involvement in the torture of her husband, a senior official said Wednesday.
Ghulam Muhammad Mohtarem, the home secretary of Sindh province, said the government would assemble a new team of investigators for the Oct. 18 attack in Karachi by two suicide bombers on a truck carrying Bhutto through a sea of more than 150,000 supporters welcoming her back from more than eight years in exile.
At least 136 people were killed, raising doubts about Pakistan's stability as it heads toward crucial elections.
The government is battling militants based in the northwest, where it sent 2,500 troops into a remote valley Wednesday to combat followers of a militant cleric calling for Taliban-style rule. But the cleric, Maulana Fazlullah, appeared to be unruffled, and thousands of his supporters gathered to hear him speak just a few miles from where the soldiers were deployed.
Authorities have accused Fazlullah of links to Islamabad's radical Red Mosque, which was stormed by army commandos in July in an operation that left more than 100 people dead.
That incident and the deployment of army reinforcements to Swat and the North Waziristan region touched off a wave of violence that has left more than 1,000 people dead.
Bhutto has blamed militants for the attack on her but accused elements in the government and security services of complicity and called for international experts to help in the investigation.
She specifically objected to Manzar Mughal, a senior investigator in the Sindh province police force, claiming he had been present while her husband, Asif Ali Zardari, was tortured in custody on corruption charges in 1999.
"The investigation team will be formed anew after Manzur Mughal disassociated himself from the investigation in view of the objections raised by Benazir Bhutto on the chief investigator's credentials," Mohtarem said.
Mohtarem said the provincial government had no doubt about Mughal's competency and professionalism, but that he had decided to withdraw from the five-member investigation team to protect it from accusations of bias.
Prime Minister Shaukat Aziz reiterated the government's insistence that Pakistani authorities are capable of solving the case without the foreign help that Bhutto has requested.
"Pakistan is a sovereign country. We know what we're doing. We don't need assistance," Aziz said, adding that Mughal's withdrawal "doesn't change the very fact that we have a whole process looking into such cases."
Aziz also played down concern that heightened security will place so many restrictions on the campaign for January parliamentary elections that they will not be considered free and fair.
Officials initially proposed a ban on public rallies, but have backed down amid opposition protests. The government is working on a code of conduct with political parties to make large gatherings easier to police.
"We'll allow full campaigning. There is a misconception that we in some way may be restricting activity," Aziz said.
A police investigator in Karachi said 15 or 16 people had been detained for questioning in the blast. Some had been injured in the attack and were picked up from hospitals, though none was being treated as a suspect, the investigator said on condition of anonymity because he was not authorized to speak to the media.
He would not identify them or say where they were being held.
A second police investigator confirmed that a number of people were being questioned.
Authorities have said the attack was likely carried out by two suicide bombers. They have released a picture showing the head of one of the attackers but have yet to identify him.
Security in the city remains high after Bhutto claimed on Tuesday that she had received a new death threat. She said her lawyer received a letter from an unidentified "friend of al-Qaida" threatening to slaughter her "like a goat."
The authenticity of the letter could not be confirmed. Bhutto said the writer claimed to be the leader of the suicide bombers "and a friend of al-Qaida and Osama bin Laden."
Speaking at her heavily guarded Karachi residence, Bhutto said her opponents "are petrified that the Pakistan People's Party will return (to power) and that democracy will return."
Bhutto, whose two governments between 1988 and 1996 were toppled amid allegations of corruption and mismanagement, has returned to contest parliamentary elections after months of talks with President Gen. Pervez Musharraf that could see them working side-by-side in the next government.
With encouragement from Washington, both are urging voters to support moderates willing to battle rising religious extremism.
The troops sent to the northwest to combat followers of Fazlullah were setting up checkpoints across Swat, a mountain valley popular with tourists until violence flared there this summer, army spokesman Maj. Gen. Waheed Arshad said.
Militants responded by detonating a remote-controlled bomb near a convoy heading into the valley late Tuesday. Arshad said four soldiers were lightly wounded and security forces had detained seven suspects.
Some 6,000 of Fazlullah's supporters, many carrying weapons, poured Wednesday into a schoolyard less than six miles from where the soldiers were deployed, vowing to back the cleric.
Fazlullah, wearing a black turban and with long, flowing hair, addressed the crowd from the back of a truck, a dozen armed men deployed around him as bodyguards.
"The government has made a declaration of war," he said, according to a local journalist who witnessed the scene. "Is it a crime to sit in the home of Allah and to study the Quran?"
Fazlullah is the leader of Tehrik Nifaz-e-Sharia Mohammed, or TNSM, a pro-Taliban militant group that sent thousands of volunteers to Afghanistan to during the U.S.-led invasion in 2001.
Pakistan banned the group and jailed TNSM's founder, Sufi Muhammad, who is also Fazlullah's father-in-law, in 2002.
However, the group has re-emerged this year in Swat and Malakand, another impoverished, conservative region next to the Afghan border where the government provides few services.
As well as marshaling a band of armed militants, Fazlullah has reportedly used an FM radio station to campaign against girls education and denounce a recent polio vaccination as Western plot to sterilize Muslim children.
