After the Yugoslav National Army attacked Slovenia and Croatia, there were no more visitors to Jasenovac Memorial Site, but work continued on a regular basis until mid-July 1991. Microfilming of the entire book collection was carried out in co-operation with the Museum Documentation Centre in Zagreb.
The building of the Memorial Museum was prepared for evacuation, but before its contents could be moved to an area outside the war zone, Jasenovac and the Memorial Site were occupied on 8 October 1991. The museum inventory was transferred to Bosanska Dubica and from there, to Banja Luka. Until May 1995, Jasenovac Memorial Site was inaccessible to museum staff and conservationists.
In a report by an observation mission of the European Community published in May 1994, an inspection of the condition of cultural monuments and museums in the occupied part of the Republic of Croatia revealed that the Memorial Museum was completely empty and that there was no information on the whereabouts of the Jasenovac Memorial Museum inventory, but that the memorial area and memorial itself had not been damaged.
The Stara Gradiška Tower had been hit by several moderately destructive missiles, leading to the demolition of the supporting construction, ground floor ceiling, upper floors, buttresses and roof on the northeast side.
Representatives of the Republic of Croatia’s Ministry of Culture’s State Administration for the Protection of Cultural and Natural Heritage visited Jasenovac Memorial Site on May 17 1995 and confirmed that the entire museum inventory was missing and that the buildings of the Memorial Museum and Memorial Site had been devastated.