Prominent international war crimes experts say they have received a huge cache of photographs documenting the killing of 11,000 detainees by Syrian authorities.
David Crane, one of the three experts, said the cache provides strong evidence for charging president Bashar Assad and others for crimes against humanity - “but what happens next will be a political and diplomatic decision”.
In the 55,000 digital images, smuggled out by an alleged defector from Syria’s military police, the victims’ bodies showed signs of torture, including ligature marks around the neck and marks of beatings, while others show extreme emaciation suggestive of starvation.
The report – commissioned by the Qatar government, one of the countries most deeply involved in the Syrian conflict and a major backer of the opposition - could not be independently confirmed.
“It’s chilling; it’s direct evidence to show systematic killing of civilians,” said Mr Crane, former chief prosecutor of the Special Court for Sierra Leone.
New York-based Human Rights Watch said the US has focused too strongly on bringing the warring parties into peace talks at the expense of putting “real pressure” on the Assad government to end atrocities and hold to account those responsible.
The group also accused Russia and China of shielding their ally Syria from concrete action at the United Nations.
“The mass atrocities being committed in Syria should be a parallel focus of the peace process,” Kenneth Roth, executive director of Human Rights Watch, told reporters in Berlin.
For Syria watchers, the descent into the abyss was not inevitable, but the result of conscious decisions by a multitude of players.
“From day one, there was a level of violence used initially by the government in its suppression that was unprecedented,” said Nadim Houry, deputy director of Human Rights Watch’s Middle East and North Africa division. “Since the Balkan wars and Rwanda in the 1990s, we have rarely seen a conflict with that many people killed in such a short amount of time.”
More than 130,000 people have died in Syria’s conflict, and more than a quarter of the population of 23 million now live as refugees, either within Syria or in neighbouring countries. Fighters who took up weapons against Assad have turned their guns on each other, trapping ordinary Syrians in the violence of two parallel wars.
Protests started in the southern city of Daraa in March 2011 in response to the arrest and torture of high school students who scrawled anti-government graffiti on the school wall. Security forces responded with brute force, beating and opening fire on largely peaceful protesters, who initially demanded reforms and later moved to seeking Assad’s removal.
Chilling brutality against opposition figures came quickly in the first months of the conflict. Hamza al-Khatib, a chubby-faced teenager, was arrested at an anti-government demonstration in April 2011 and not seen again until his mutilated body was delivered to his family weeks later.
Popular cartoonist Ali Farzat was severely beaten up and had both his hands broken before being dumped on the side of the road after he compared Assad to Libya’s dictator Muammar Gaddafi.
The body of Ibrahim Qashoush was thrown in the Orontes river with his throat carved out for writing poetry and anti-Assad songs that rallied thousands of protesters.
As opponents increasingly took up arms, the government escalated its repression. War planes indiscriminately hit rebel-held residential areas with incendiary bombs and crude explosive-filled barrels, often hitting bread lines at bakeries, schools and makeshift hospitals. Government forces have been blamed for an August chemical weapons attack that killed hundreds.
Sectarianism fuelled the viciousness. Syria is a patchwork of religious groups, with Sunnis making up the majority and forming the backbone of the rebellion. Assad is a member of the Alawite sect, an offshoot of Shiite Islam.
A May 2012 assault on Houla – a cluster of Sunni villages surrounded by Alawite towns in central Syria – killed about 100 people, including many children under the age of 10. Video showed rows of dead children with gaping head wounds in a mosque, and the UN called it a massacre by pro-Assad gunmen. In a massacre blamed on rebels, nearly 200 civilians were killed in pro-regime villages in Latakia province.
Islamic militants and foreign al Qaida-linked fighters joined the war against Assad – and reports of human rights abuses by the opposition soared, including mass killings of prisoners, beheadings and floggings. In Aleppo last year, al Qaida-linked gunmen killed a 15-year-old coffee vendor in front of his parents, accusing him of being an “infidel” for allegedly mentioning Islam’s Prophet Muhammad in vain.