A number of Syrian opposition figures have taken refuge in Istanbul as the government of Syrian President Bashar al-Assad targets dissidents. (Chris McGrath/Getty Images)

A prominent Syrian activist and her journalist daughter were found dead in their Istanbul apartment late Thursday, according to Turkish media reports.

Police discovered the bodies of 60-year-old Orouba Barakat and 23-year-old Hala Barakat, a U.S. citizen, after friends and family in Turkey and Syria raised the alarm following several days without contact, according to residents of their Uskudar neighborhood and the semiofficial Anadolu news agency.

Orouba Barakat was an outspoken member of the Syrian National Coalition, an opposition body that has taken part in internationally brokered peace talks with President Bashar al-Assad's government.

Hala Barakat, who was raised in Raleigh, N.C., was a well-regarded journalist with the opposition outlet Orient TV. In recent months, her Twitter postings commemorated the lives of civil defense workers killed in bombings by pro-Assad forces and lamented the destruction of the northern city of Aleppo, much of it a rebel stronghold until it was recaptured after a punishing government bombardment in December.

Local news reports suggested that the two women had been strangled and stabbed, and their bodies covered with a chemical agent to diminish the smell of decomposition. 

News of the killings sent shock waves through the community of activists who have sought sanctuary in Turkey as dissidents are targeted by Assad's security forces in their native Syria.

It also reverberated through Syrian communities in North Carolina and Southern California that were already no strangers to tragedy. In social-media postings, relatives of three young Arab Americans fatally shot by a neighbor in Chapel Hill, N.C., in 2015 said that Hala and Orouba Barakat had also been their cousins.

"Numbness. Confusion. Shock. Disbelief. I can't think straight," Suzanne Barakat wrote. "How many more beloved family members will I lose to hatred and violence?"

Although police did not immediately attribute responsibility for the killings, they appeared to be the fourth to target Syrian opposition activists on Turkish soil in the past four years. 

Islamic State militants have previously singled out media activists for retribution after reports about the extremist group's crimes inside its self-proclaimed caliphate spanning Syria and Iraq. 

In Istanbul, Uskudar residents implicated the Syrian government, fearing that loyalists could now reach them abroad.

Friends of the Barakat family, speaking on the condition of anonymity out of fear for their safety, said they had been instructed to stay in their homes and await the results of the state forensics report.

For others, suggestions that the killings could have been carried out by local criminals brought little solace. 

"Even if it was a criminal case, this just shows how vulnerable Syrians are here," said Mohammed Shibli, 24, a Syrian activist in Istanbul. "I do not feel safe anymore. I think it is better to leave Turkey."