Oliver and Rosemarie Zammit, the Maltese-Australian parents of Doujon Zammit, have faced the alleged killers of their son during their trial on the Greek island of Lesbos, Australian media reported.

The Australian Daily Telegraph said they clasped each other's hands for support as they took front row seats in the packed courtroom. Sitting behind them was Kostas Gribilas, who received Doujon's heart, and his new wife Poppy.

Marios Antonopoulos, a bouncer, is accused of beating Doujon, 20, with a fold-out baton on the island of Mykonos in August last year. Antonopoulos, 26, has been charged with murder while another three men face charges of being accessories to murder and attempted murder. All have pleaded not guilty.

Defence counsel sought to stop the trial, arguing that key witnesses were not present, but the presiding judge rejected the request.

Doujon's cousin Cameron Tabone, who was with him during the assault, could not attend for financial reasons and provided a written statement. Also missing were three other Australian witnesses and a Greek resident who called an ambulance on the night.