A judge will investigate claims by a secretary - said to have made a clandestine phone call for help from an unknown location - that she is being held by graft-busters against her will. Mr Justice Michael Hartmann, of the Court of First Instance, will hear evidence today from the Independent Commission Against Corruption on whether Becky Wong Pui-sze is in their custody and the legal basis for keeping her. Ms Wong, a secretary for Derek Wong Chong-kwong, chairman of listed company Semtech International Holdings, was arrested with her boss and seven other people last Friday over alleged payments of more than $1.5 million to bankers and analysts to manipulate Semtech's share price. The commission has said the nine have since been released on bail. But a writ of habeas corpus was filed on Wednesday alleging Ms Wong was being held against her will. A hearing will be heard today after the writ was upheld in the face of an ICAC appeal yesterday. A legal source said Ms Wong was in the ICAC's witness protection programme. In a habeas corpus case, a judge orders the person to be brought before the court to investigate the right of the authorities to keep that person imprisoned. In a letter filed by barrister Kevin Egan to the ICAC and seen by the South China Morning Post, Mandy Chui Man-si, described as Ms Wong's 'business partner', said she had been contacted by Ms Wong on Sunday night, saying she had been 'held against her will'. The letter says an initial attempt by Ms Wong to make the call on her mobile phone was foiled when ICAC officers confiscated the telephone's SIM card. She had another card and managed to call from a toilet. 'Ms Wong was adamant she was being detained against her will and that she wished to leave 'protective custody',' the letter said. The case was adjourned until 3pm today for a full hearing.