They would have found a lot of evidence and witness accounts of Israeli use of chemical, as well as biological and nuclear, weapons against the Palestinians and their Arab neighbors. The attacks started in May 1948 and are still going on in one form or another.
In May 1948 the Zionist gangs besieged the well-fortified Palestinian city of Acre, which could stand the siege for a long time. The city water supply came from a nearby village name Kabri through an aqueduct. To shorten the siege and to enter the city, the Zionist gangs injected typhoid in the aqueduct. Many Palestinians and some 55 British soldiers, who were in the city, got infected. This crime was called operation “Shlach Lachmecha” as described by the Israeli military historian Urin Milstein [Wendy Barnaby’s “The Plague Makers: The Secret World of Biological Warfare”, London, Vision Paperbacks, 1997, pp 114-116]