On April 9, 1989, troops from the Soviet Ministries of Defense and Interior used entrenching spades and, it was alleged, toxic gas, to break up a peaceful demonstration of 8,000 to 10,000 people in Tbilisi, Soviet Georgia. Sixteen people were known to have been killed on the scene. Another four people later died from injuries sustained on that day. Hundreds of people were injured and admitted to hospitals.
Physicians for Human Rights was asked by Dr. Andrei Sakharov and Dr. Irakli Menagarishvili, Minister of Public Health for Soviet Georgia, to provide technical expertise in assessing the possibility that toxic gas or gases had been used against the crowd. After weeks of attempting to obtain travel visas, on May 17, 1989, a team of three PHR physicians arrived in Tbilisi.