Bashir Sheikh, a senior local official, said Friday that another person injured in the attack had passed away, bringing the death toll to 143.
Bhutto, who was unhurt, and her associates have lambasted the inquiry as "inept," citing confusion over whether one or two suicide bombers carried out the attack.
"That's the view they hold as lay people. But as a professional law enforcement officer I don't consider that as appropriate. It's not right," Farooqi said.
Bhutto's camp has maintained their criticism even after police replaced Manzur Mughal, the head of the five-member team probing the blast. Bhutto accused him of involvement in the torture of her husband in 1999 while he was in custody.
Farooqi said Mughal was a decent officer and would have carried out the investigation professionally but the cacophony of criticism heaped upon him risked undermining the inquiry.
Bhutto has accused elements in the government and security services of trying to kill her. She has demanded that international experts join the investigation -a call rejected by the government.
Farooqi said his force had solved every suicide bombing they had looked into.
"This is the ninth one we've investigated and we are pretty hopeful we can work it out," he said.
The blast has raised concern that fear of more attacks will restrict the campaign for January parliamentary elections.
Bhutto has vowed to continue campaigning though acknowledged she will have to adapt her plans to improve security.
She is expected to travel begin traveling the country on Saturday with a trip to her ancestral home in Larkana, about 430 kilometers (270 miles) northwest of Karachi, to visit the tomb of her father.
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