Pakistan's main state prosecutor in the 2007 murder of former prime minister Benazir Bhutto and the 2008 Mumbai attacks was shot dead in Islamabad en route to court Friday, police said.
Chaudhry Zulfiqar was shot multiple times after gunmen intercepted his vehicle shortly after he left home in a busy, middle-class neighbourhood of the capital. His bodyguard was also wounded and a woman passer-by killed.
The assassination comes just days before Pakistan holds historic general elections on May 11, marking the first time that a civilian government completes a full-term in office and hands over to another at the ballot box.
Zulfiqar was given extra government security last year after he was mentioned in threats received by police investigators working on the Bhutto case.
The source of the threats was unclear, but one investigator said he was told not to appear in court at Zulfiqar's behest by an unknown caller using a number in Afghanistan.
"Chaudhry Zulfiqar was driving his car. He lost control and the car crushed a woman passer-by," police officer Mohammad Yousuf told AFP.
Medics said he died of his injuries before arriving at hospital.
The gunmen, who are believed to have attacked from at least two different angles, fled and officers refused to speculate who was responsible.
President Asif Ali Zardari, Bhutto's widower, condemned the killing and ordered a thorough investigation to "expose the real culprits involved in the murder", his office said.
Zulfiqar had been on his way to the latest hearing of the anti-terrorism court hearing the Bhutto case in the neighbouring city of Rawalpindi.
He lost control of his car after being shot and hit the woman, who died instantly, witnesses and officers said.
Abdul Mateen, who works at a nearby guest house, said he heard heavy gunfire.
"When I came out I found a car moving out of control. It then descended into a side road. The man in the drivers' seat was bleeding profusely with multiple bullet injuries on his head, shoulder and the back," he said.
"People rushed to the area, put him into a taxicab and took him to hospital."
Zulfiqar's white Toyota Corolla was badly damaged in the attack.
Its wind shield was smashed and there were multiple bullet marks on both sides of the car and at the front. Pieces of broken window lay inside and on the road. There was blood on the car seats and on the road, an AFP reporter said.
Former military ruler Pervez Musharraf was this week placed under two-week house arrest over charges that he conspired to murder Bhutto.
"We very strongly condemn this incident. We are colleagues. If it can happen to him today, it can be us tomorrow," Musharraf's lawyer Afshan Adil told AFP.
Nobody has ever been convicted or jailed for Bhutto's assassination in a gun and suicide attack after a campaign rally in Rawalpindi on December 27, 2007.
Musharraf's government blamed the killing on Pakistani Taliban chief Baitullah Mehsud, who denied any involvement and was killed in a US drone attack in 2009.
Bhutto's son, Bilawal Bhutto Zardari, who is chairman of the outgoing main ruling Pakistan People's Party, has accused Musharraf of her murder.
In 2010 a UN report said Bhutto's death could have been prevented and accused Musharraf's government of failing to give her adequate protection.
Zulfiqar was also the main government prosecutor who indicted seven alleged conspirators in the 2008 Mumbai attacks, which killed 166 people and which were blamed on Pakistan's Islamist group Lashkar-e-Taiba.
Pakistan indicted the seven in 2009 but has since said it needs to gather more evidence in India before proceeding further.
India accuses Lashkar-e-Taiba of training, equipping and financing the attack with support from "elements" in the Pakistani military.
"I cannot comment. I'm in a state of shock," Zulfiqar's deputy Azhar Chaudhry told AFP when asked to comment.
Musharraf, who ruled from 1999-2008, returned to Pakistan on March 24 to contest next week's election, but has been barred from running for parliament and is under house arrest in the Bhutto case and for sacking judges in 2007.
The Taliban have threatened the main parties in the outgoing government and attacks directly targeting politicians and political parties have killed more than 60 people since April 11, AFP tally said.