BEIRUT // A young woman was found beheaded and mutilated in Syria, underscoring what witnesses and the United Nations human-rights office said was a fearsome new government tactic of retaliating against protesters' families.
Zainab Al Hosni, 18, is believed to be the first woman to die in custody since the uprising began in mid-March.
Amnesty International said on Friday she had reportedly been detained by Syrian security agents to pressure her activist brother to turn himself in.
Her parents found her body by chance in the same morgue as that of her brother, after they had been summoned to identify his corpse.
The violence serves as a grim reminder of how the Al Assad family has kept an iron grip on power in Syria for more than 40 years by brutally crushing every sign of dissent.
The idea that the regime has eyes and ears everywhere resonates in a nation of 22 million, where decades of autocratic rule have nurtured a culture of deep fear and paranoia.
Witnesses and activists have said retaliation against the families of those involved in the uprising has ranged from threatening phone calls to beatings and even killings, as in the case of Al Hosni.
The UN human-rights office said on Friday that the harassment was extending beyond Syria's borders.
"Prominent human-rights defenders, inside and outside the country, are reported to have been targeted," the spokeswoman Ravina Shamdasani said in Geneva.
"We are also concerned by reports of the targeting and attacking of families and sympathisers of the protesters by security forces."
The Syrian opposition movement has proved remarkably resilient despite a massive military assault against them.
According to UN estimates, more than 2,700 civilians have been killed in the crackdown since March and thousands more have been detained.
Al Hosni was from the central city of Homs, one of the hotbeds of the protest movement. She was seized by men in plain clothes on July 27, apparently to pressure her brother Mohammed, who was organising protests in the city, Amnesty said.
After her arrest, he was told by telephone that she would be released only if he stopped his activities, the New York-based group said.
Her brother was eventually arrested this month. On September 13, his mother was summoned by security forces to pick up his body, which showed bruises, burns and gunshots, the group said.
At the same morgue, the mother happened to find her daughter's body as well.
The family said Zainab had been decapitated, her arms cut off, and skin removed, according to Amnesty.
After Zainab's burial last weekend, women held a protest in Homs, hailing her as the "flower of Syria" and chanting "Syria wants freedom" ", according to video footage posted on the internet by local activists.
"They plucked the flower, and she said, 'After me, a bud will rise up.' Rejoice in eternal paradise, Zainab," read a sign held by one of the women.
The deaths of Zainab and her brother bring to 103 the number of people who have been reported killed in Syrian custody since the uprising began, Amnesty said.
"If it is confirmed that Zainab was in custody when she died, this would be one of the most disturbing cases of a death in detention we have seen so far," said Philip Luther, Amnesty's deputy director for the Middle East and North Africa.
* Associated Press