Two Syrian ex-intelligence officers accused of crimes against humanity will appear before a German court this week, in the first such trial over state-sponsored torture in Syria.

When Anwar al-Bunni crossed paths with fellow Syrian Anwar Raslan in a DIY store in Germany five years ago, he recognised him as the man who had thrown him in jail a decade earlier.

On Thursday (April 23rd), the two men will face each other in a German court, where Raslan will be one of two alleged former Syrian intelligence officers accused of crimes against humanity for the Syrian regime of Bashar al-Assad.

In the first legal proceedings worldwide over state-sponsored torture in Syria, Raslan will be tried under the principle of universal jurisdiction -- which allows a foreign country to prosecute crimes against humanity.

For Bunni, the trial will send "an important message" to the Syrian regime: "You will never have impunity, so think about it!"

Bunni said Raslan was the man who arrested him at his Damascus home in May 2006 and threw him in a state prison, where the lawyer spent five years until he was freed during the Syrian uprising in 2011.

The two men arrived in Berlin within two months of each other, and crossed paths when they were briefly staying in the same centre for asylum seekers.

"I told myself that I knew this man, but I did not recognise him instantly," Bunni said. A few months later, he came face to face with his alleged captor once again -- this time in a store -- and finally recognised him.

'Exposing the truth'

A Syrian lawyer in his sixties, Bunni was an indefatigable advocate for human rights in his home country, but has lived as a refugee in Berlin.

Unable to pursue his profession in Germany, he now collects evidence and testimonies against the regime.

While Bunni will not be one of the plaintiffs in Thursday's trial, he is a respected figure in Germany's 700,000 strong Syrian community, and has convinced numerous victims to come forward.

In 2016, when he started working with local lawyers, Bunni learned that German investigators already had their eye on Raslan, who was arrested in February 2019.

Raslan now stands accused of having overseen the murder of 58 people and the torture of 4,000 others while in charge of al-Khatib detention centre in Damascus between 2011 and 2012.

Another Syrian, Eyad al-Gharib, 43, is accused of having been an accomplice.

"This is not about revenge, it is about exposing the truth," said German lawyer Patrick Kroker, who represents six Syrian plaintiffs.

Now refugees in various European countries, these victims of Syrian regime torture "want the world to learn about what happened there", Kroker said.

'Physical mistreatment'

All those who are set to testify in Koblenz were "subjected to physical mistreatment, in some cases very brutally and over a long period" in the state prison, Kroker said.

Their supposed crimes included "taking part in demonstrations, filming demonstrations... or collecting medicines for those injured at demonstrations", he added.

Many victims have preferred to remain silent, terrified of reprisals against friends and family members back in Syria, or of retribution from Syrian regime agents in Europe.

For Bunni, the fight is far from over.

Around a thousand Syrians implicated in the crimes are now living carefree lives in Europe, he claimed. Meanwhile, people are still being tortured at al-Khatib.

The witnesses in Koblenz are speaking not only for themselves but also for their fellow victims, Kroker said.

"Most of them said: 'I am also doing this... to make it clear what this means for many others who perhaps cannot be here, either because they are still imprisoned, because they have to be afraid, because they cannot come to Europe or because they died under torture.'"

International investigations

Courts in France and Spain also have opened investigations into alleged crimes committed by the Syrian regime.

In 2016, the UN set up its International, Impartial and Independent Mechanism, which is preparing war crimes charges against individuals over the Syrian conflict.

Since April 2018, the UN body has been gathering evidence for use in possible future trials of those alleged responsible for crimes against humanity.

It contains more than a million items, including documents, photographs, videos, satellite images, statements from victims and witnesses and unclassified documents.