A German court has sentenced a Syrian former intelligence officer to life in prison in a case the UN rights chief said could lead to accountability for other perpetrators of the war’s “unspeakable crimes”.

Anwar Raslan, a former colonel loyal to the regime who later defected and gained asylum in Germany, was deemed by the judge at Koblenz higher regional court to have verifiably overseen the murder of at least 27 and torture of at least 4,000 prisoners at a detention facility in Damascus.

It is the first case to find a senior official in the regime of Bashar al-Assad guilty of crimes against humanity.

The landmark verdict further lists Raslan’s crimes against humanity as entailing 25 cases of dangerous bodily harm, two cases of rape and sexual coercion, two cases of sexual abuse, 14 cases of deprivation of liberty lasting longer than a week, and two cases of kidnapping.

“Today’s verdict should serve to spur forward all efforts to widen the net of accountability for all perpetrators of the unspeakable crimes that have characterised this brutal conflict,” said UN high commissioner for human rights, Michelle Bachelet, calling the verdict “historic”.

The ruling was welcomed as a symbolic step towards justice by torture survivors.

“This day, this verdict is important for all Syrians who have suffered and are still suffering from the Assad regime’s crimes”, said Ruham Hawash, a former prisoner at al-Khatib detention facility – Raslan oversaw as a commanding officer between 29 April 2011 and 7 September 2012 – and joint plaintiff in the case. “It shows us: justice should and must not remain a dream for us.”

Last February the same court in Koblenz sentenced, Eyad al-Gharib, a 44-year-old former low-ranking officer in the Syrian intelligence service to four months and six years in prison for aiding and abetting a crime against humanity.

Both Raslan and Gharib were tried under the legal principle of universal jurisdiction, which allows the prosecution of crimes in one country even if they happened elsewhere.

Over 108 trial days in the town in Germany’s south-west, the judge heard statements from almost 50 witnesses who had survived the Branch 251 facility, several of whom appeared as co-plaintiffs. They described how suspects rounded up by the regime were beaten by guards with fists, sticks, cables, and metal pipes, and held in tightly packed cells whose ventilation shafts were intermittently closed to induce panic.

The Koblenz trial also saw the photographs of the Syrian military photographer known only by his codename Caesar who smuggled shocking evidence of torture out of Assad’s dungeons, presented to a court as evidence for the first time.

Witnesses called on by the defence painted a more humane picture of the man in charge of the Branch 251 facility. One, a former air force officer turned novelist, said Raslan treated him well during his detention and interrogation at al-Khatib, offering him tea and cigarettes and conversing about literature.

Raslan protested his innocence, arguing he had secretly harboured sympathies for the Syrian opposition and tried to support its cause after defecting. He fled to Jordan in 2012 and in 2014 was granted asylum on humanitarian grounds in Germany, where he said he did not try to cover up his past.

One witness, the Syrian businessman and political dissident Riad Seif, confirmed in front of the court that he had helped Raslan’s effort to enter Germany in 2014 on a visa issued by the German embassy in Amman, by forwarding documents relating to his asylum application to the foreign ministry in Berlin.

Seif said he had supported the defected general’s case in the hope of gaining valuable information relating to the fate of other political dissidents inside al-Khatib. However, Raslan had failed to deliver: “We got nothing from Anwar Raslan, not a word.”

“Universal jurisdiction is often the last hope for victims of the most serious crimes,” said Wolfgang Kaleck, the general secretary of the European Center for Constitutional and Human Rights (ECCHR), which assisted several of the co-plaintiffs in the trial.

“In any case, today’s judgment creates a solid basis for other European prosecutors to pursue further proceedings. Dealing with crimes in Syria in third countries is not ideal – but possible, and a duty towards those affected.”

Germany’s federal criminal police started investigating Raslan in 2017, after he described his role in Syria’s security apparatus in detail during an interview with Stuttgart police, supposedly to aid their investigations into another officer. He was arrested in February 2019.