On May 10, the UNSC held a debate concerning the report about which I recently wrote. I think this is some additional information from Karim Asad Ahmad Khan, Special Adviser and Head of the United Nations Investigative Team to Promote Accountability for Crimes Committed by Da’esh/Islamic State in Iraq and the Levant (UNITAD):

Information obtained from ISIL electronic devices has also led to the opening of a new investigation into the development and successful deployment of chemical and biological weapons by ISIL in Iraq, he said.  Evidence collected to date details how ISIL used laboratories at Mosul University as the epicentre of its chemical weapons programme, drawing on the expertise of scientists and medical professionals from Iraq and abroad.  Initially weaponizing chlorine from water treatment plants overtaken in 2014, ISIL subsequently developed toxic lethal compounds including thallium and nicotine that were tested on live prisoners, leading to death.  As its capacity strengthened, it developed a sulfur mustard production system that was deployed in March 2016 through the firing of 40 rockets at the Turkmen Shia town of Taza Khurmatu.