BEIRUT (AP) — Syrian activist Yashar hopes the security agents who tormented him during five months of detention will one day be put on trial. In detention, he says, he was locked naked in a tiny box for a week, beaten daily during marathon interrogations and blindfolded for 45 days.

A whole range of groups have accelerated a campaign to gather evidence of war crimes including torture, massacres and indiscriminate killings in the Syrian regime's war against rebels, hoping to find justice if President Bashar Assad falls. Some talk about referring the cases to the International Criminal Court or forming a special tribunal, but many in Syria hope that it's all laid out in the country's own courtrooms.

"I want to take my case to a Syrian court and a Syrian judge who will put my torturers in the same jail where I was held," Yashar, 28, told The Associated Press. He declined to give his full name for security reasons.

Some 70,000 people have been killed and thousands of others maimed, injured or missing in Syria since the uprising against Assad began in March 2011, according to the United Nations. Both the U.N. Human Rights Council and the Independent International Commission of Inquiry on Syria have published multiple reports documenting crimes committed during the civil war, including the slaughter of more than 100 civilians in the central region of Houla last May blamed on pro-regime militiamen.

A recent U.N. report accuses both sides in the war of atrocities but says those committed by rebel fighters have not reached the "intensity and scale" of the regime's.

The amount of data is massive, and the challenges are immense. The Syrian government has not given permission to the U.N. commission to visit Syria and has largely closed the country to independent journalists, further complicating the work of rights groups.

Even so, groups of determined Syrian activists continue quietly to collect the evidence.

One group, the Violations Documentation Center in Syria, has documented 49,763 deaths excluding soldiers, 35,508 detentions and 982 people missing in lists that include the name of the deceased, status, the region they come from, date of death and cause of death.

Razan Zaytouni, the general coordinator, said the group collects its material through interviews with families, eyewitness accounts and activist videos as well as photos documenting evidence of beatings, torture and other violence.

Among the difficulties her group and others face is getting people inside Syria to come forth, particularly in Damascus where the regime is still strong, and obtaining evidence that would stand up in court.

"All these lists and information would serve two purposes in the future," Zaytouni, who has been living in hiding since shortly after the uprising began, said via Skype. "First is to prosecute the criminal regime and second to keep our country's collective memory and history alive through videos, photos and names."

Representatives from Zaytouni's group along with others doing similar work held a meeting in Turkey last month during which they launched the National Preparatory Committee for Transitional Justice, tasked with collecting all the dates and information available from all the groups.

"Collecting evidence in Syria is now being done by activists, and there is a need for practitioners to categorize the crimes," such as torture, rape, arbitrary arrest and random shelling, said Radwan Ziadeh, the Washington-based director of the Damascus Center for Human Rights Studies.

David M. Crane, a former prosecutor at the Sierra Leone tribunal, which indicted former Liberian President Charles Taylor in 2003, said among the challenges is the multitude of inexperienced activists collecting a flood of evidence in an uncoordinated way.

To help with building a case for a future prosecutor, Crane created an organization called the Syrian Accountability Initiative.

"We have mapped the entire conflict, we have built a crime base and we have actually sample indictments for whoever will get the case, be it a Syrian or international prosecutor," said Crane, an international law professor at Syracuse University in New York state. He said that the information is being shared with the International Criminal Court, the United Nations and the Syrian opposition.

On Feb. 18, U.N. investigators called on the Security Council to refer Syria to the International Criminal Court. Because Syria is not party to the Rome Statutes that established the ICC, the only way the court can investigate the situation is if it receives a referral from the Security Council, which has been paralyzed by divisions when it comes to Syria.

Some Council members argue that such a move would further encourage Assad's regime to dig in and resist to the end. Continued...