(ANSA-AFP) - SOFIA, FEB 10 - Bulgarian investigators suspect four people found dead in a remote mountain region killed themselves, while two others, including a 15-year-old boy, were murdered. The case -- which one prosecutor has described as something out of the TV series "Twin Peaks" -- has gripped the Balkan country and shone a spotlight on a group that hosts holiday camps for youngsters. The bodies of two men, aged 51 and 22, and of a 15-year-old boy were found on Sunday in a camper van parked in a remote area of the Stara Planina mountain range in western Bulgaria. "Based on the autopsy data for the three bodies, it appears that there were probably two murders committed successively and one suicide," the prosecutor's office announced Tuesday, citing the results of the autopsies of the bodies. On February 2, police had already discovered the bodies of three men, aged 45, 49, and 51, in the courtyard of a private burned-out mountain hut near the Petrohan Pass in the same mountain range. "There are no signs of a struggle or any trauma other than the gunshot wounds," Sofia high court deputy prosecutor Natalia Nikolova told a press conference on Monday, indicating that those three, too, had committed suicide. According to investigators, security cameras around the hut showed all the six people who died remained together until the morning of February 1. Part of the group, including the 15-year-old boy, then left in a camping van, while the others stayed at the shelter before setting it on fire. The case, described on Sunday by the national police chief as "an unprecedented crime, at least for Bulgaria", has sparked a wave of speculation on social media, including criticism of the police investigation. Most of the victims belonged to an NGO called the National Protected Areas Control Agency (NAKZT), which hosts holiday camps in the countryside for youngsters. (ANSA-AFP).