Most of the bodies were buried in an antitank trench several kilometers long, which the Yugoslav authorities concealed and kept secret.

Additional research on the burial sites was conducted in 2007 by the Commission on Concealed Mass Graves in Slovenia.

In May 1945, at the end of World War II in Yugoslavia, soldiers of the Independent State of Croatia began retreating towards Austria, where British forces were located, with the intention to surrender to them rather than the advancing Yugoslav Partisans.

[3] Together with many civilians, the Croatian Armed Forces (HOS) fought their way to the Yugoslav–Austrian border and surrendered on 15 May to the British Army.

[4][5] Around 25,000 reached the border, mostly the town of Bleiburg, while around 175,000 were spread in nearby columns that were dozens of miles long.

The transit centres were located in a military barracks in the Studenci District, an aircraft parts factory in Tezno and several smaller buildings.

A former Partisan who witnessed the killings gave a description of one of them: [...]prisoners were lined up at the edge of the hole where the older corpses lay.

Screams rent the air, providing grim evidence that those who had dodged the machine gun fire had not eluded death for long.

Then the Partisans directed several more bursts of machine gun fire into the pile of bodies, just to make sure that they had not left anyone alive.

[1] The Tezno mass graves were found during the construction of a motorway near Maribor in 1999, when workers came upon an anti-tank trench that stretched several kilometres.

The Commission on Concealed Mass Graves in Slovenia reported that their analysis and conducted probing of what is now a forested area in Tezno found human remains at a length of 940 meters.

The historian Mitja Ferenc notes that among the victims were also some members of the Montenegrin National Army, who were incorporated into the HOS that year, and probably a few members of Muslim militias, the German Army, and the Hungarian and Albanian battalions of the HOS (Hungarista legion and Skanderbeg legion).

The Tezno Woods 2–6 Mass Graves (Slovene: Grobišče Tezenski gozd 2–6) lie west of the settlement of Dogoše, between the Zlatoličje hydroelectric plant canal and Maribor, and are part of a former antitank trench.

[21] In September 2007, the Slovene government started plans to make the mass grave site in Tezno a memorial park and a cemetery.

[22] Croatian president Ivo Josipović visited the site in June 2010 and laid wreaths for the victims.

At the opening of the memorial park in June 2012, the President of Slovenia, Danilo Türk, said:[25]The end of the Second World War also witnessed extra-judicial killings.

On every suitable occasion, as the President of the Republic of Slovenia, I condemn all extra-judicial killings, and all forms of war and revolutionary violence.