This is how credible the Western investigation of of human rights abuses by the Syrian regime is

"To get documents, Mr. Wiley’s team has built alliances with rebels who oppose President Bashar al-Assad, notably those of the Free Syrian Army, although it recognizes that some rebel groups have also committed atrocities. “Sometimes, like the police, you have to ally yourself with bad guys to get the guys that are badder,” Mr. Wiley said in one of several interviews."