A Libyan lawyer was shot dead in her car in the eastern city of Benghazi on Tuesday, a security source told AFP, confirming local media reports.
The lawyer, Hanan al-Barassi, "was shot dead in Road 20, one of the main commercial streets in Benghazi," said the security source, who asked to remain anonymous.
"Moments earlier, she had been broadcasting a live video via Facebook."
A media figure in Libya, 46-year-old Barassi was known for giving voice to female victims of violence in videos that she then broadcast on social media.
She also ran a local association for the defence of women's rights.
In the footage posted to her Facebook page just before she was shot, Barassi speaks to the camera while seated in her car.
She criticises armed groups close to east Libya-based military strongman Khalifa Haftar, saying she had been "threatened".
Barassi's killing comes nearly a year and a half after the disappearance of lawmaker Siham Sergewa, who was abducted from her home in Benghazi by armed men.
Before her abduction, she had slammed an offensive launched by Haftar in April last year to take the capital Tripoli from the United Nations-recognised Government of National Accord (GNA).
Sergewa's whereabouts are still unknown.
The murder of Barassi sparked an outcry across Libya, with many on social media demanding justice.
The news of Barassi's killing "is appalling and a painful reminder of the reality on the ground especially for women," said fellow Libyan lawyer Elham Saudi, who is also known for her defence of human rights.
"With no accountability, violators will continue to get away with literal murder in broad day light."
Hanan Salah of Human Rights Watch called the incident "frightening and chilling".
It is "reminiscent of other crimes of this kind for which nobody has ever been punished. Authorities in the east must investigate quickly and hold the criminals accountable," she wrote on Twitter.
Libya has been wracked by conflict since the overthrow and killing of dictator Moamer Kadhafi in a NATO-backed uprising in 2011.
It has since been dominated by armed groups and divided between two administrations that have been bitterly-opposed: the GNA in Tripoli and a rival administration in the east backed by Haftar.
After the failure of Haftar's offensive to seize the capital, fighting ended in June and a permanent ceasefire was agreed in October.
Libyan representatives from all sides began direct talks in Tunisia on Monday, under the aegis of the UN, aimed at finding a political solution to the conflict.