Halliburton consists of two major divisions, KBR, which provides logistics and construction services, and the Energy Services Group, which concentrates on support services for oil explorers.
This will create new issues for those companies in industries like logistics and construction where there is much interaction with officials, says Charles Hecker at Control Risks, an international risks consultancy.
Authorities say they believe Yalcin had been the logistics man of the group, and had been living legally in Spain where he worked for a construction company in Gibraltar.