Article 42 of the Rome Statute of the International Criminal Court outlines qualifications and procedures for the election of the Prosecutor of the ICC.

http://www.un.org/law/icc/statute/romefra.htm

Qualifications: He/she must be an individual of high moral character with extensive practical experience and competency in the prosecution or trial of criminal cases and excellent knowledge and fluency in at least one working language of the Court.

Procedures: the Prosecutor is elected by secret ballot by an absolute majority of the members of the Assembly of States parties.