An initial investigation has ruled out foul play in the case of 121 skulls discovered last week in Gansu province , a senior public security official said yesterday. The skulls were found abandoned with their crowns sawn off, and religious specialists said lamas were known to use skull caps as bowls or ceremonial artifacts. Security official Liu Shuo said: 'The possibility of a crime can be excluded, based on the initial investigation.' Last Monday, the skulls were found in plastic bags on a riverbank in Tianzhu Tibetan Autonomous Prefecture on the border of Gansu and Qinghai . One of the skulls had a moustache and another had false teeth attached. None is thought to be from a recently deceased person. Mr Liu said forensic expert Chen Shixian identified the skulls as human and said they bore no signs of fatal injuries. Buddhism researcher Zhao Min said some practitioners of Tibetan Buddhism used craniums to 'destroy desire and remind us that life is unpredictable'. Mr Zhao said cups made from skull caps were not mandatory tools for Buddhist lamas and were not in widespread use. Cups and beads made from human skulls can be found on the online shop taobao.com for more than 1,000 yuan. According to a Beijing man who sells items on taobao.com, the beads are made from the skulls of lamas, who donated them to be made into items to protect people. He said the skull caps of ordinary people were also sometimes made into cups or beads, but they were usually dangerous because their histories were unknown. He said he believed that because the Gansu skulls had been abandoned, Buddhists could not have been involved: 'This is very evil. And the punishment it brings about must be huge.'