Simon Wiesenthal went to great lengths to track down war criminals and find surviving witnesses who could testify against them. Like other Jewish historical commissions, the JHD collected testimonies from survivors in the DP camps. The collected information was then systematically sorted according to the name of war criminals and the locations of the crimes. At the same time, Wiesenthal not only continuously solicited information about war criminals from survivors living outside the DP camps, from various state agencies and Jewish organizations, but he also shared information with many individuals and institutions engaged in the same matter.
As the “Linz collection” shows, Wiesenthal himself testified in several trials and provided other investigating authorities with testimonies as well as documents on war crimes.