Interpol is just a clearing house which co-ordinates co-operation between the law enforcement agencies of different nations.  Jurisdiction would belong to the nation from which the crime is deemed to have been committed or to have taken place (where there are multiple jurisdictions involved, one place can cede jurisdiction to another).

Jurisdiction doesn't become an issue until a criminal investigation has been conducted.  Mt Gox is the only party so far which acknowledges having filed a police report.  I suspect that the release of this information will prompt people to file reports with the appropriate computer crime units in their own countries (I know one person had already reported the Bitcoinica hacks to the DoJ in the US).  It's those law enforcement agencies who'll determine if any charges are laid and where.

It would certainly be wise for Zhou to retain a lawyer at this point.