The slaying of a Libyan women's rights activist in her home just hours after she voted in a general election drew Western and UN condemnation on Thursday.
Masked men broke into the home of Salwa Bugaighis in restive second city Benghazi, an Islamist bastion, just hours after polls closed on Wednesday evening.
"Mrs Bugaighis was stabbed in several parts of her body but the cause of death was a bullet wound to the head," said a spokesman for the Benghazi Medical Centre.
US ambassador Deborah Jones called the killing "heartbreaking" on her Twitter account and denounced "a cowardly, despicable, shameful act against a courageous woman and true Libyan patriot".
British ambassador Michael Aron tweeted that he was "Devastated about horrific murder of Salwa Bugaighis. Leadinglight of Revolution & human rights champion. Sad day for # Libya.”
Bugaighis, a lawyer and a feminist, played an active part in the NAT0-backed uprising of 2011, which ended the four-decade dictatorship of Moamer Kadhafi.
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A former member of the National Transitional Council, the rebellion's political wing, she was vice president of a preparatory committee for national dialogue in Libya.
Benghazi was the birthplace of the uprising but it has become a stronghold of Islamist militia and was the scene of a deadly 2012 attack on the US consulate.
Tensions have been raised further by an armed campaign launched by a rogue former rebel commander last month to rid the city of Islamists which has drawn many regular army units to his side.
The regular army in Benghazi has been hit by repeated deadly attacks, as have civilian officials and Westerners.
The UN Support Mission in Libya expressed regret that "once again, Benghazi witnesses a bloody attack, the (latest) of a series largely targeting civilians".
"UNSMIL calls on Libyan authorities to thoroughly investigate the assassination and bring the perpetrators to justice."