After his jungle arrest on Saturday, Ta Mok wasformally charged on Tuesday under a 1994 law outlawing the Khmer Rouge and is being held in a city centre military jail. Investigators say he faces the prospect of further charges in a military court, including those relating to his role as Pol Pot's chief of staff during the murderous `Killing Fields' regime when up to two million people died. ``Charges could range from tax evasion, kidnapping, torture and thousands of charges of homicide: the case against him is enormous,'' a military prosecutor said. ``He will need a very good lawyer and we will need a very thorough investigation.'' Despite shunning recommendations by a panel of UN experts for an international tribunal, the Cambodian government has requested ``international assistance'' to put Ta Mok on trial.