Detectives have turned to the World Health Organisation and the United States' Food and Drug Administration in an effort to speed up their investigation into the controversial Church of Zion. Officers conducting the inquiry into the use of hydrogen peroxide by church members admitted yesterday to being stumped by the technical complexities of the case. And they say any decision on whether a crime has been committed can only be arrived at when they understand the exact physical properties of hydrogen peroxide. But almost three weeks into the investigation they say little progress has been made. New Territories North Senior Superintendent Andy Tsang Wai-hung, in overall charge of the investigation, said: 'We do not even know what the exact physical properties of this pharmaceutical product are. 'So naturally we will not be able to consider which laws may or may not have been broken until that is done. We have been asked to look at this from a health and legal angle; we do not want to get involved in church politics,' he said. Mr Tsang said the Health Department would be asked to contact the World Health Organisation, the Food and Drug Administration and the British Department of Health. 'They may have information on this particular pharmaceutical that we don't have,' he said. 'Until we have that information we cannot take the investigation on to the next stage.' Several members of the church have been questioned informally. Church of Zion leader Leung Yat-wah claims hydrogen peroxide is a cure for diseases such as cancer and AIDS.