The man, identified by media as Svetozar Djordjevic, was beaten up outside his apartment building in Zagreb around 8 p.m. on 6 January, when Orthodox Christians celebrate Christmas Eve. He was hit from behind by a hard object and kicked several times by unidentified assailants, after which he lost consciousness.
After he came to, Djordjevic went home, but did not call either the ambulance or the police. He passed out again that night and was transferred to a hospital where he was kept for observation.
Police said at a press conference that they had launched the investigation after learning of the incident from journalists as neither Djordjevic nor the hospital had reported the attack.
According to media reports, Djordjevic suspects he was beaten up by two of his neighbours who had already attacked him twice in December. One of the neighbours is a retired war veteran while the other is a retired police officer.