In the recording, Sato confirmed that he assumed command of the unit in December 1941. Kawamura presented evidence stating that after Japanese forces occupied Hong Kong in late 1941 and implemented a policy to reduce the local population, Sato, who had previously investigated a Salmonella outbreak in Hamamatsu and was familiar with the pathogen, directed the mixing of Salmonella bacteria and cholera pathogens into meals distributed to refugees.

　　The operation allegedly caused at least several hundred deaths, with some estimates placing the death toll at more than 10,000. During the Khabarovsk Trial after World War II, Sato denied responsibility for biological warfare for multiple times.

　　Testimony by Kurihara, subordinate of Sato, described conditions inside the human experimentation facilities. Test subjects, he said, were confined in iron cages measuring approximately 1.5 meters square and kept in leg irons. In one control experiment, subjects who were given only distilled water reportedly died of physical exhaustion after about 20 days. Kurihara also recalled sealed containers holding human specimens transported from Manchuria, including the bodies of children.

　　Journalist Fuyoko Nishisato, who interviewed Kurihara twice, said at the gathering that many former Unit 731 personnel escaped prosecution through secret postwar arrangements between the US and Japan. She argued that a number of those perpetrators later assumed influential positions in Japan"s public health establishment and some of them kept downplaying radiation-related health risks following the Fukushima nuclear leak.