Police appear no closer to catching the killer or killers of a family bashed to death as they slept in their North Epping.Relatives of the family are being kept in a safe place as police fear for their safety while autopsies on the bodies of the Lin family - Min, 45, his wife Yun Li "Lillie", 43, their sons Henry, 12, and Terry, 9, and Lillie's sister, Yun Bin Yin, 39, - continue.Police are examining the family's past, business dealings and relations to discover if someone close to them had a motive to want them dead.The head of the homicide squad, Detective Superintendent Geoff Beresford, said forensics would hold the key but a strike force of 18 detectives was throwing everything at the case."It's very difficult to determine [whether the crimes were committed by one or more people] and that's why we rely so heavily on the forensics in this case," Superintendent Beresford told Sky News. "We don't have any eye witnesses obviously, but the victims themselves can tell us so much in terms of forensic examination and that process is a long, laborious process." Henry and Terry had attended Epping North Public School, but Henry had started at Epping Boys High School this year. The couple's eldest child, Brenda, 15, who had been on a study trip to New Caledonia with her high school, Cheltenham Girls, returned home on Sunday.Superintendent Beresford said she was not under police guard but was safe with relatives in a secret location. "We do have concerns for her safety in so far as this is such an unusual and such a vicious attack, and we have taken steps to ensure her safety," he said. It is understood two other relatives, Shu Lin and Lian Bin Xie, are also in hiding, and that police are keeping a watch on international borders, with concerns that the killer or killers may try to flee the country.The autopsies are expected to be completed by Friday. Yesterday forensic staff continued their examinations of the three upstairs bedrooms in which the family were killed as they slept, some time between midnight on Friday and 8am on Saturday.Police had yet to identify a suspect or motive, Superintendent Beresford said. "It's not clear to us at this point in time and that's why it's critical to work very methodically through the profiling process," he said. "But also we're heavily reliant on anybody who has information about the family that assists in building up that profile."Superintendent Beresford told Sky News members of the public had provided valuable information, but he appealed for anyone else who had seen anything suspicious in the days leading up to the attacks to contact police.He confirmed that two family members who were seen being escorted by police through the family's newsagency, on Rawson Street, were helping to identify business documents to assist with the investigation.Police are making inquiries in China as to whether Yun Bin Yin had a boyfriend or husband there. They did not explain why she was living at the house.