None of these reports have been verified. Amnesty International hasn't even been in Syria for many years.
The credibility of the “Caesar” story has been substantially based on the Carter-Ruck Inquiry Team which “verified” the defecting photographer and his photographs. The following facts suggest the team was biased with a political motive:
the investigation was financed by the government of Qatar which is a major supporter of the armed opposition.
the contracted law firm, Carter Ruck and Co, has previously represented Turkey’s President Erdogan, also known for his avid support of the armed opposition.
the American on the legal inquiry team, Prof David M. Crane, has a long history working for U.S. Dept of Defense and Defense Intelligence Agency. The U.S. Government has been deeply involved in the attempt at ‘regime change’ with demands that ‘Assad must go’ beginning in summer 2011 and continuing until recently.
Prof Crane is personally partisan in the conflict. He has campaigned for a Syrian War Crimes Tribunal and testified before Congress in October 2013, three months before the Caesar revelations.
by their own admission, the inquiry team was under “time constraints” (CRR, p11).
by their own admission, the inquiry team did not even survey most of the photographs
the inquiry team was either ignorant of the content or intentionally lied about the 46% showing dead Syrian soldiers and attack victims.
the inquiry team did their last interview with “Caesar” on January 18, quickly finalized a report and rushed it into the media on January 20, two days prior to the start of UN sponsored negotiations.
The self-proclaimed “rigor” of the Carter Ruck investigation is without foundation. The claims to a ‘scientific’ investigation are similarly without substance and verging on the ludicrous.
The U.S. Central Intelligence Agency (CIA) is involved.
https://www.counterpunch.org/2016/03/04/the-caesar-photo-fraud-that-undermined-syrian-negotiations/