Shahin arrived in Toronto in March with nothing but his guitar.

He came from Syria, making an almost year-long detour in Ankara, Turkey. The guitar is a constant reminder of a friend, Kamal, who was tortured and killed in a Syrian prison.

Shahin — not his real name, to protect his family back home in Damascus — plays songs Kamal used to sing. The friends met in their late teens during the early days of the Arab Spring and attended one of the first rallies against the Syrian regime in early 2011.

Shahin, a Syrian refugee and not his real name to protect his family back home, came to Canada with his guitar. He has stories to tell of beatings suffered by himself and his friend Kamal. A Canadian man who helped to form the Commission for International Justice and Accountability says stories by victims account for only a part of the evidence of war crimes committed by the Syrian regime. In fact, the commission seeks government documents that are smuggled out of the country. But it would be Shahin's only rally. In Damascus, where people were already taking sides, neighbours in his own apartment building threatened Shahin's father if he let his son go again.

"They said that if I went to another protest they would kill him and my entire family, said Shahin, speaking in Arabic. ""My father told me that I was putting my entire family at risk by protesting."

Shahin and Kamal continued following the action on Facebook. Kamal, less cautious than Shahin, sometimes posted his own comments against the regime.

At university where Shahin was studying statistical analysis, he slipped up once, calling President Assad a giraffe - a common joke in Syria about the president's unusually long neck. He was reported, and held blindfolded in a prison outside Damascus, where he was beaten for three days before being released..

Potential for prosecution

Shahin, a Syrian refugee now in Toronto, sings songs on his guitar that remind him of his friend Kamal, beaten to death in a Syrian prison. Syrian refugees have terrible stories to tell but those seeking evidence of war crimes committed by Syria need government documents to prove their case. As for Shahin, he says: "I've been out of Syria for a while now, but I still wake up in the morning and ask where am I? Will I hear a bomb? Will I hear of someone's death? Will I open Facebook and find a eulogy?"

When the uprisings first began, many Syrian men were swept up in mass arrests and held, sometimes for days and weeks without their families knowing if they were dead or alive. Many, like Shahin, were released after brutal beatings as a warning to other Syrians to keep quiet. But many others were executed.

"Frankly," said Bill Wiley, co-founder of the Commission for International Justice and Accountability (CIJA), which has spent three years collecting war crimes evidence in Syria, "Shahin got off easy for that joke."

Through CIJA, which includes legal experts and investigators who've worked for war crimes tribunals in Rwanda and the former Yugoslavia, Wiley saw an opportunity to improve the quality of future war crimes investigations, working more quickly for a fraction of the cost.

Wiley, raised in Toronto and Newfoundland and a former officer with the Canadian Army, left the military to get his PhD in international criminal law. He'd also worked for Canada's War Crimes Program investigating World War II crimes before moving to Europe to join the International Criminal Court (ICC). Over the course of his career, Wiley says he's seen a growing loss of faith among western governments in the efficacy of international criminal justice.

Through CIJA, Wiley trained a team of about 40 Syrians, as well as a handful of ad hoc members, to gather evidence that will hold perpetrators at the highest levels of the Syrian regime to account.

For now, without the political will of key UN Security Council members like the U.S., Russia, and China, the International Criminal Court has no jurisdiction in Syria.

But for Wiley, the political impasse was an opportunity to prepare for criminal justice before there is political consensus to see it through.

"I saw the potential early in the Syrian conflict," said Wiley, "because of the jurisdictional vacuum and no international body taking action. By now, this work has turned into something much bigger than anticipated."

'Suppress the uprising'

In this photo released by the Syrian official news agency SANA, Syrians gather in front of a burning car at the scene where suicide bombers blew themselves up, in the coastal town of Tartus, Syria, Monday, May 23, 2016. Syrian TV said suicide bombers blew themselves followed by a car bomb in a parking lot packed during morning rush hour. (SANA via AP) (Syrian official news agency (SANA) via Associated Press)

At the core of an international criminal case, said Wiley, are documents that help reveal the command, communication and control structures of the people responsible.

"Once you understand those structures, you understand the perpetrators. The victims don't come into the investigation until late in the day," said Wiley. "Stories from people who are victims is a small percentage of our work — about 10 per cent."

In fact, the evidence required to hold leaders responsible for the horrific abuses carried out on the front lines tends to the clinical and undramatic.

"No one ever says, 'kill all those people'," said Wiley. "What we do is follow the direction that comes from the top and the reports that go back up. [President Bashar] Assad is at the top, and he's not a figurehead. He's very much involved."'

"At the top," said Wiley, "officials set out broad policies with directives like 'suppress the uprising'. But nowhere do you find orders that people should be tortured to point of death. The orders are expressed in more functional, scientific language but they're clear about the objectives."

Moving paper

A boy carries his belongings at a site hit by what activists said was a barrel bomb dropped by forces loyal to Syria's President Bashar al-Assad in Aleppo's al-Fardous district, Syria April 2, 2015. (Rami Zayat/Reuters)

Young Syrian activists working for CIJA have collected 600,000 pages of military, security intelligence and regime material, often taken when government buildings were abandoned early in the uprising or seized by opposition fighters.

Their average age is 30, most of them unmarried and adept on social media, and also, said Wiley, "committed to contributing to a Syria based on the rule of law."

The young activists also smuggle the documents out of the country, especially dangerous because of the weight of paper.

He estimates about 2.5 tonnes of material has been moved out of the country. "And they're having to move out of the sector where they know what's going on."

Wiley takes pride that only one of the activists on his team has been killed, and three wounded.

"We've done very well," said Wiley, "given how risky it is. My first responsibility as director is to make sure no one gets hurt. It comes down to good planning - very, very careful planning. And also luck."

The greatest danger right now is not from the regime but from radical jihadists in the north of Syria.

"If our people are caught with these documents, they're seen as regime agents or western spies," said Wiley. "You can't even begin to explain the idea that we're using them to apply criminal justice."

As for a timeline for justice in Syria, Wiley says that will likely have to wait until the fighting stops.

This image released by the International Committee for the Red Cross shows the first humanitarian aid convoy in Daraya, Syria on Wednesday, June 1, 2016. A besieged suburb of Syria's capital received humanitarian aid Wednesday for the first time since 2012, as the United Nations. The International Committee for the Red Cross (ICRC) reported that a joint convoy with the U.N. and the Syrian Arab Red Crescent entered the Damascus suburb of Daraya in the afternoon. The U.N. estimates that 4,000 to 8,000 people currently live in the suburb.(ICRC via AP) (The Associated Press) Meanwhile, CIJA has already completed five case files, including one focused on the very top of the regime, including President Assad.

"I would like to see an end to the war," said Wiley. "I'd like to do something else with my life. But absent a military defeat to the regime, we need to settle in and expect a good deal more fighting to come, another year or two."

And while the stories of Syrian victims make up only a small percentage of preparing a case against the regime, they are the reason Wiley's team painstakingly reconstructed the paper trail connecting the abuse on the ground to the officials responsible.

"We're already seeing cases starting to be brought because of the diaspora of Syrians into Europe," said Wiley. "A lot of mid-level and of course low-level perpetrators are starting to show up in Europe, and if they haven't already, they will start to turn up in Canada through the refugee flows."

CIJA has already begun supporting and informing authorities in Europe with prosecutions. But ultimately, Wiley predicts, there will be some kind of international court with jurisdiction to prosecute these cases.

Post-traumatic stress

Although Shahin escaped the grinding conflict in Syria, he may never escape the memory of what happened to his friend.

"A hundred days later — exactly 100 days," after his friend disappeared, said Shahin, "his parents called me. They asked me to come with them to pick up his body. Imagine a friend — five years being friends, your best friend — and then he was taken. Why? Because he posted stuff on Facebook."

But now safe in Toronto, Shahin also marvels at the change within himself.

"I was unconscious when the revolution started 'til now. And now finally I'm starting to wake up. I've been out of Syria for a while now, but I still wake up in the morning and ask where am I? Will I hear a bomb? Will I hear of someone's death? Will I open Facebook and find a eulogy?"