Gunmen have killed a woman politician who was a senior member of former cricket star Imran Khan’s upstart Pakistani political party.
Police said Zohra Shahid Hussain was shot outside her home in the southern port city of Karachi on May 18.
The gunmen escaped, and there was no immediate claim of responsibility.
Hundreds of mourners, including activists from Khan's party, attended Hussain's funeral, held in a Karachi mosque late on May 19.
Police said it was unclear whether the killing was a targeted murder or the result of a robbery.
Hussain was a vice president of Khan’s Pakistan Movement for Justice (Tehreek-e Insaf, or PTI) party in Sindh Province.
Her killing came ahead of scheduled re-voting in Karachi on May 19 that follows allegations of vote-rigging in Pakistan's elections earlier in the month.
That balloting was continuing as scheduled despite Hussain's killing.
The PTI emerged as a new political force in the elections, rising from marginal status to become Pakistan’s third-largest party.
In a written statement, Khan blamed Karachi political rivals for the killing, and said he was "totally shocked and deeply saddened and still cannot believe anyone would kill such a gentle lady."
Khan put the blame on the Muttahida Qaumi Movement (MQM) party, the leading political power in Karachi.
He specifically named party head Altaf Hussain, who lives in exile in London, accusing him of threatening the PTI.
Khan added that he held the British government responsible for failing to take action against Altaf Hussain, who is wanted on murder charges in Pakistan.
Khan tweeted on his official account:
I also hold the British Govt responsible as I had warned them abt Br citizen Altaf Hussain after his open threats to kill PTI workers.— Imran Khan (@ImranKhanPTI) May 18, 2013
A senior police superintendent, Aftab Ahmed Sheikh, told reporters it was unclear whether the killing was a murder or a robbery attempt that may have gone awry.
"With the evidence that we have collected so far, we can not rule out both scenarios -- that it could be a murder or that it could be an incident of robbery," he said. "Our investigation is under way, but further on, once we collect more evidence, we will be able to tell what it is."
The Pakistani Election Commission ordered Sunday’s partial voting rerun after the PTI and the right-wing Jamaat-e-Islami party staged protests claiming vote-rigging in the May 11 elections.
The MQM has denied allegations of widespread rigging and says it will boycott the re-vote.
The May 11 elections were marred by a campaign of violence by Islamists aimed at intimidating voters to stay away from polls. Despite pre-poll violence and election day attacks that killed around 150 people, voter turnout in the elections was 60 percent.
The elections marked the first time in Pakistani history that an elected government completed its full term and handed over power to a new civilian administration.