Police concluded Ivancic was murdered after finding grave injuries to the body, notably to the head, probably caused with a stone.
An autopsy confirmed the priest was murdered and that the murder was probably committed by several persons, Bihac county prosecutor Senad Ljubijankic said on Sunday. He could not say if Ivancic was murdered for gain because it has still not been established if anything is missing from the parish house.
Police believe the murder was committed on Friday.
Ivancic was born in Zavalje in 1935. He became a priest in 1963 and had been the Zavalje parish priest since 1997.
On February, two persons broke into the parish house in the night. The priest was in his bedroom but was unable to recognise them because they were masked. They have still not been found. A few days before Christmas, about HRK 25,000 (about 3,330 euros) was stolen from the house.