INVESTIGATIONS into the death of a 23-year-old British woman who died after being found unconscious in the bed of Radio 3 presenter Harvey Crump are focusing on an evening of night-clubbing during her final hours. The case, which remains unclassified, has been referred to a district crime squad of about 10 officers for further investigation, but it may be up to eight weeks before detectives are able to pinpoint the exact cause of Lisa Jane O'Riordan's death. In the meantime, dozens of people have been interviewed as investigators attempt to piece together her exact movements prior to her death. Mr Crump, 38, the host of a weekday music and chat show, told police he woke last Saturday morning to find O'Riordan lying unconscious in the bed beside him. The pair had been out drinking together several hours earlier, but Mr Crump said he left her and went home to his Whampoa Gardens flat only to have her ring later and ask if she could stay with him. Mr Crump told police he unlocked the door for her and went back to sleep and knew nothing more until he woke with her beside him. Detectives said O'Riordan had spent the evening with a group of friends at several nightclubs and bars in Lan Kwai Fong and that friends who were with her that night had been interviewed. Police have not ruled out that she may have died of a drug overdose. Small bruises were found inside her throat and efforts are being made to identify any medical condition she may have had. 'There may be a link from the night before and we have to make sure that possibility is fully investigated,' a police spokesman said. 'We are not treating it as a murder investigation but it is important that nothing be missed in this sort of case. A lot of checks have to be done.' Initial results of the postmortem examination do not give an indication of how she died. She was certified dead at 11.22 am at the Queen Mary Hospital - about an hour after Mr Crump is said to have discovered her.