A member of the Free Syrian Army runs after placing a mortar shell inside a launcher during what activists said were clashes with pro-government forces beside Hanano barracks in Aleppo's Karm al-Jabal district on Tuesday. (SAAD ABOBRAHIM/REUTERS)

One of the most prominent figures in the peaceful protest movement that swept Syria early in the country’s uprising was reported missing Tuesday from a rebel-controlled suburb of Damascus, prompting suspicions that she is among the scores of civilian activists and journalists who have been detained by Islamist extremists in recent months.

Razan Zaitouneh, 36, a human rights lawyer, disappeared from her apartment with her husband and two other activists overnight Monday after threats were received from Islamist groups, according to the opposition group of which she was a founder, the Local Coordination Committees.

A friend who lives in the same building had visited the activists Monday night and found them gone Tuesday morning. He said that the apartment had been ransacked and laptops and files taken, but that money and valuables were not touched.

The apparent targeting of a woman so closely associated with the peaceful origins of the revolt ricocheted through the already demoralized activist community, drawing condemnations on Twitter and Facebook, as well as soul-searching.

“Razan’s kidnapping is like the slap in the face we need to wake up and acknowledge what this conflict has become,” said Rami Nakhla, an LCC co-founder who now lives in Istanbul. “It’s become a regional sectarian war using the cover of our legitimate demands for democracy — a giant, bloody monster.”

Scores of the activists who helped shape the initial uprising against President Bashar al-
Assad’s rule have been detained by extremists in rebel-held areas in recent months, exposing the gulf that has emerged between those advocating democratic
reforms and the Islamist radicals who have eclipsed them. Most have disappeared in the north of the country, where the al-Qaeda-affiliated Islamic State of Iraq and Syria (ISIS) has gained ascendancy over more moderate rebel units.

Dozens of foreign journalists and aid workers also have been abducted in northern Syria. On Wednesday, the families of two Spanish journalists missing for nearly three months publicized their disappearance for the first time, appealing for their release.

Javier Espinosa, the Middle East bureau chief of El Mundo newspaper, and Ricardo García Vilanova, a freelance photographer, have not been heard from since they were detained at an ISIS checkpoint in September. There have been unconfirmed sightings of them in ISIS prisons, but no demands have been made, Espinosa’s wife, Mónica Prieto, said at a news conference in Beirut.

ISIS has a far smaller presence in the Damascus area than in the north. Douma, the suburb where Zaitouneh disappeared, has long been a stronghold of Jaish al-Islam, which has taken a lead role in a new Islamist alliance called the Islamic Front, now the country’s biggest rebel formation.

A spokesman for the group, Islam Alloush, denied involvement and said he did not know which group was responsible. Jabhat al-Nusra, another al-Qaeda-affiliated group, has a small presence in the area, said Zaitouneh’s friend and neighbor, also a longtime activist, speaking on the condition of anonymity because he fears for his safety.

Most recently, Zaitouneh had been working for another project she founded, the Violations Documentation Center, which catalogues the tens of thousands of deaths and disappearances in Syria’s war. The threats against her began after she started investigating abuses by rebels, colleagues said.