Yugoslav consulate in Klagenfurt sent diplomatic protests to the Austrian government, but the commemorations were never banned by Austria. The commemoration was seen as a provocation by Yugoslavia. Prohibited Croatian symbols were openly displayed and it drew attention to postwar killings which the Yugoslav authorities denied. The Bleiburg events were also used as a tool for historical revisionism and the focus of collective resentment by the remainder of the Ustaše and their supporters. The number of victims was artificially inflated. The Yugoslav State Security Administration (UDBA) monitored the activities of the participants of the commemorative event and conducted a series of attacks on its organizers. During the ceremony in 1966, a bomb exploded in a country inn in Loibach, but none of the attendants was injured. Nikica Martinović, the chairman of the Bleiburg Honorary Guard, was assassinated by the UDBA in Klagenfurt in 1975. The following year a bomb was found in front of the tavern of Mirko Karačić, also a member of the Bleiburg Honorary Guard. In spite of the threats and attacks, the commemoration continued to be held annually until the breakup of Yugoslavia. Gatherings and commemorations were also held in other countries. In 1960, on the 15th anniversary commemoration held in Cleveland, the Bleiburg Tragedy Research Committee was founded by Croatian emigrants. In 1961, the commemoration in Cleveland was attended by US Congressman Michael A. Feighan. The Yugoslav consul in Pittsburgh, Ivan Mirošević, protested against it and requested the gathering to be banned. Feighan criticized the consul and Josip Broz Tito during his speech at the commemoration. Mirošević was expelled from the US for his comments. In 1965, commemorating the 20th anniversary, US Senator Frank Lausche condemned the post-war killings in Yugoslavia. Organizations of Croatian emigrants in Germany and USA requested a Red Cross investigation of mass grave sites, which was rejected by Yugoslavia. In 1976, a marble monument was erected in the Unter-Loibach cemetery and in 1987, a monument was erected on the Bleiburg field with the inscription "In Honor and Glory of the Fallen Croatian Army, May 1945" in Croatian and German language. The monument had the Croatian coat of arms and the Islamic star and crescent engraved. Investigations of mass graves Discussions about the post-war massacres were forbidden in Yugoslavia, so the investigations of mass grave locations began only in the 1990s, after the fall of communism. In 1992, 1163 bodies were excavated from