DETECTIVES are investigating horror claims of sex-abuse and murder of a teenage girl after skeletal human remains were recovered from Lough Gill in Co. Sligo.Although Gardai (police) still cannot say whether the remains are male or female, they believe the bones are those of 14-year-old Melissa Mahon, who disappeared more than 18 months ago from her home in Sligo town.Initially it was thought the youngster, who hadn't settled since her family moved into the area two years earlier, had returned to England.But the focus shifted dramatically three weeks ago when two sisters with whom Melissa was acquainted told detectives she had been murdered by their father.The sisters, now aged 15 and 16 and in the care of authorities, also claimed they had been raped by their own father and that he was the parent of a baby the youngest girl gave birth to recently.The girls gave detectives precise details of how they claim the murder was carried out. They said their father, who had been conducting an illicit affair with Melissa, strangled her in an upstairs bedroom of their home in September 2006 and wrapped the body in a blanket or sleeping bag.They said he then forced them to help him carry the bundle down the stairs where it was put in a car trunk before being driven to the shores of Lough Gill and dumped in the lake made famous by W.B. Yeats in his poem "The Lake Isle of Innisfree."Just two weeks after the sisters' claims the skeletal remains were recovered close to a spot where they said Melissa's body was dumped. Pieces of a sleeping bag were also recovered.However, despite private suspicions, police insist the remains cannot be identified until extensive DNA examination is carried out.In a bizarre twist to the saga the main suspect in Melissa's disappearance and murder has given lengthy interviews -- anonymously -- to the local Sligo Weekender and to the Sunday World newspapers.He admitted he had "a history" in England before his return to his native Sligo five years ago, but he denied raping his daughters or killing Melissa.He claimed one of his own daughters should be the main murder suspect. "She has changed her story a number of times. The one thing I know is that she has an intimate knowledge of what happened to Melissa. She should be investigated for this murder and not me," he said.