15 years later, in 1961, the Bosanska Dubica SUBNOR conducted a minor research of Donja Gradina. Three mass graves were discovered and opened. Apart from skeletons, victims’ personal belongings were, also, found in the graves, which suggested that those people were not prisoners who did not have such items because they were taken away from them immediately upon their arrival to the camp.

Three years later, in 1964, new researches were conducted in Donja Gradina. 130 drillings were carried out on 100 gravesites providing an insight as to the content, depth and type of those graves. Anthropological researches were conducted during the period from 22 June until 27 June 1964. Probes were opened at locations marked by previous drillings. The remains of bones of victims lied, in most of the cases, over each other in disorder, mutually intertwined, in different positions and at different levels. They lied there as they had been thrown in the pit. Social and ethnic structure of victims was able to determine on the basis of their personal and everyday objects found next to skeletons in mass graves. Remains of clothes, shoes, jewellery and other everyday objects show whether the victims originated from a village or a city area. On 29 and 30 June 1964, an expertise of skeletons dug up in Gradina was performed. Complete and partial fractures were found on most of the skulls found in the opened probe.

12 years later, from 25 August until 05 September 1976, locations suspected to be graves were drilled for probes. Graves of around 50m2 were opened at four locations. The remains that were found were analysed. Various injuries were established. In most of the cases they involved depressions in the skulls, in the back of the head and on the temples. Fractures were detected on other bones and ribs, too. Based on a bone analysis, it was established that skeletal remains of young persons and children prevailed in this grave.

In 1986, workers of the Jasenovac Memorial Site in Donja Gradina opened one grave. Bones and bone fragments were packed in 10 metal boxes and sent to the Institute for Forensics and Criminology of the Faculty of Medicine, University of Zagreb, for an analysis. Institute members who examined and analysed the bones established that the boxes contained skeletal remains of 152 persons. Traces of fractures caused by an impact with a hard object were established with certainty on 58 examined skulls. One skull was completely preserved, with entirely preserved brain. Traces of bleeding were found in the brain tissue and cerebral ventricles. This bleeding was pressurizing the brain which was the direct cause of death. The person that the skull belonged to had sustained an injury due to an impact with a blunt hard object in the parietal-occipital region. According to the volume of bleeding between the bones of the right part of the skull and the brain, it can be claimed with certainty that after having sustained the injury, this person lived for at least 2-5 hours more. In this specific case, it was a woman of young age.