Police questioned three men over the bombing of Benazir Bhutto's caravan as her aides pressed authorities on Sunday for a full investigation into the attack that killed at least 136 people and shattered her triumphant return from exile. The men were linked to a vehicle that police believe was used by one of the attackers, who threw a grenade at the convoy late on Thursday, a senior investigator said on Saturday on condition of anonymity, due to the situation's sensitivity. The men were brought in for questioning on Saturday night.
Police detained the three men in southern Punjab province — a center for militancy — and took them to Karachi, where the bombing occurred, for questioning.
The senior investigator said police believed the men, who have not been charged, hold crucial clues to the bombing.
Bhutto, who served twice as prime minister and is Pakistan's main opposition leader, left in 1999 to avoid arrest in corruption cases registered against her by the then-government of Nawaz Sharif, ousted by current President Gen Pervez Musharraf in an October 1999 coup.
However, Bhutto has held talks with Musharraf in recent months to discuss how to share power after parliamentary elections due in January.
On Sunday, Bhutto's top aides went to a Karachi police station demanding the bombing be investigated to the fullest.
The aides brought a statement, signed by Bhutto, asking that police "register the case and investigate so that the accused and their conspirators may be brought to book and punished according to the law."
Police officials said the case had already been registered, but that the statement would be added to the file.
However, the aides noted that police had not yet met with Bhutto to discuss the attack.
"The police never approached Benazir Bhutto," said Kaim Ali Shah, a top leader in Bhutto's Pakistan Peoples' Party.
The bombing was the deadliest in Pakistan's history, turning Bhutto's jubilant homecoming parade into a scene of carnage. At least 136 died and more than 200 were wounded.
On Saturday, Pakistan's government denied involvement in the attack, while sporadic violence flared in Karachi, a boisterous city of 15 million people.
Angry over the suicide bombing, supporters of Bhutto's party threw stones and burned tyres in parts of the city.
Fourteen people were shot in a neighborhood that is one of her strongholds after outsiders mixed with Bhutto supporters. Police said the outsiders began firing shots.
"They (Bhutto supporters) are expressing their anguish over the attack on their leader and the deaths of so many people," said Fayaz Khan, a senior Karachi police officer.
Authorities say the bombing bore the hallmarks of a warlord and the Al-Qaida terror network.
Bhutto blamed Al-Qaida and Taliban militants for the assassination attempt, but also hinted that government or military officials could have been involved.