 Complete the following phrase:  In the early 1990s, Action Saybusch was investigated by the Commission for the Prosecution of Crimes Against the Polish Nation at the Institute of National Remembrance in Katowice followed by a formal inquiry initiated in 1998 by Senator Władysław Bułka. After a series of announcements in the press, some 1,000 persons contacted IPN with personally collected data and supplementary materials, revealing the identities of many displaced families. According to Ewa Koj from IPN most living victims had already been interviewed. The investigation was limited by their advancing age and had to be discontinued on legal grounds. However, it was followed by a broad exhibit of documents and photographs collected in the process, and presented in many regional cities and towns including Katowice, Żywiec, Bielsko-Biała and others. The Nazi perpetrators of ethnic cleansing had already been sentenced during the 