Was it the Syrian rebels who used Sarin gas on their own people?
That's a determination from the UN human rights commission looking into war crimes in Syria. They should not be confused with the UN commission set up by Secretary General Ban Ki Moon to specifically investigate the use of chemical weapons in Syria.
Is this a difference without a distinction? It may not be.
U.N. human rights investigators have gathered testimony from casualties of Syria's civil war and medical staff indicating that rebel forces have used the nerve agent sarin, one of the lead investigators said on Sunday.
President Bashar al-Assad's government and the rebels accuse each another of carrying out three chemical weapon attacks, one near Aleppo and another near Damascus, both in March, and another in Homs in December.
The United Nations independent commission of inquiry on Syria has not yet seen evidence of government forces having used chemical weapons, which are banned under international law, said commission member Carla Del Ponte.
"Our investigators have been in neighboring countries interviewing victims, doctors and field hospitals and, according to their report of last week which I have seen, there are strong, concrete suspicions but not yet incontrovertible proof of the use of sarin gas, from the way the victims were treated," Del Ponte said in an interview with Swiss-Italian television.
"This was use on the part of the opposition, the rebels, not by the government authorities," she added, speaking in Italian.
Del Ponte, a former Swiss attorney-general who also served as prosecutor of the International Criminal Tribunal for the former Yugoslavia, gave no details as to when or where sarin may have been used.
The Geneva-based inquiry into war crimes and other human rights violations is separate from an investigation of the alleged use of chemical weapons in Syria instigated by U.N. Secretary-General Ban Ki-moon, which has since stalled.
In order to prove the rebels used gas, you have to make a convincing case that they were able to acquire some. It puts the whole thesis in question and raises the possibility that the "independent commission" based in Geneva is being choosy about who they interview about the attacks.
There are many reasons to deflect blame from the Assad regime for chemical weapons attacks, not the least of which is the probability that if the commission were to blame the Syrian government, it would force the west to take military action. I don't know if you've noticed or not, but the overwhelming majority of diplomats at the UN much prefer peace at any price to going to war. Deliberately obfuscating the facts to prevent a wider war is not beyond the realm of the possible.
Then there is the solidarity factor with many states supporting Assad or, more likely, opposing the increasingly jihadist nature of the rebels. Blaming them for the attack suits many political agendas.
I'm not saying it's impossible for the rebels to have gotten their hands on some Sarin gas, and a delivery system for them - special artillery shells the most likely - except the rebels have very few heavy artillery pieces. It just strikes me as unlikely.
How and when they acquired the gas, how it was deployed, and which witnesses are accusing the rebels of using it all have to be answered before a definitived judgment can be made.