Dear Ravish,
Very well I have understood your point. Being the head of a particular department, the individual has the privilege to fix the number and prescribe the additional qualifications of the prospective personnel " saleable " and make indents to the HR as if they are required actually for his department. Maitain a secret log in this regard with the approval of the HOD of HRD and make entries in that relating to the periodicity of man-power indent placed by him, the no. of candidates required and their additional qualifications, if any repeatedly mentioned, if he also sits in the recruitment process the peculiarity or speciality of his approach to some candidates seemingly preferable to him, the actual cost of on-the-job training or orientation progrrame suggested and imparted by him to the freshers, the frequency of their leaving and the reasons cited by them, the list of companies they immediately join and the similarity or competitive nature of their operations to your company, the nature and position of the fresh appointments offered to the migrantrs, the nature of credentials if any suggested by him to be mentioned in the experience certificate to be issued to the resignees etc., and analyse them critically and if your preconceptions were correct certainly you can find a conspicuous pattern of similarity or uniformity in every case of such wilful exit. Unless and otherwise some reliable inside information in this regard, you would not have become suspecious of this "man-power hi-jack" of the individual. So, try to reduce his role in the matter of fresh appointments. As a first step for instance, in determining man-power requirement of every department, form a committee of senior executives of that particular dept along with its HOD. Prescribe a long tenure of bond period and reimbursemement of training cost together with interest and long notice period in case of premature or immediate resignations. If your C.E.O is a straight-forward and impartial person having no personal affinity with the individual, bring the entire surreptitious and illicit activities of the individual and its adverse impact on the organization to his notice in the most opportune moment. That's all what I can suggest!