Federal Investigation Agency special prosecutor Chaudhry Zulfiqar Ali, who had been scheduled to appear in an anti-terrorism court Friday, was critically wounded after being hit by bullets fired by the motorcycle-riding gunmen and was later declared dead at a hospital, Geo News reported.
In the shooting, an unidentified woman also died, while Ali's guard was injured, Dawn newspaper reported. The guard was quoted as saying Ali had been receiving threats lately, but other details were not immediately available.
Bhutto, former Pakistani prime minister and wife of current Pakistani President Asif Alif Zardari, died in a gun and suicide attack Dec. 27, 2007, in the garrison city of Rawalpindi, after she had addressed an election rally. She had earlier returned to Pakistan after a long self-imposed exile.
The Bhutto assassination has been under investigation since then.
Friday's killing of the prosecutor comes as Pakistan, already wracked by deadly militant and sectarian attacks for years that have killed hundreds of people, has also lately been hit by election-related violence.
General elections are to be held May 11, and they are significant in that it will mark the first time there will be a democratic power transition since the country's founding in 1947. The previous civilian government was the first to complete its full five-year term in March in a country that has been ruled intermittently for decades by the powerful military.