The international body charged with establishing who is responsible for chemical attacks in Syria says it has identified seven potential sites for investigation, which it hopes to begin next month.

Virginia Gamba leads the Joint Investigative Mechanism of the U.N. and the Organization for the Prohibition of Chemical Weapons. She spoke to reporters Monday.

An initial report to the U.N. Security Council had identified five cases where chemical weapons might have been used. Further analysis led to two other suspected cases: in Binnish in Idlib governorate on March 23, 2015 and in Al Tamanah, also in Idlib, on April 29-30 and May 25-26 in 2014.