Federal investigators have been looking into American oil companies' real estate dealings in Equatorial Guinea to determine whether they have improperly benefited the country's despotic ruler...Both firms [Marathon Oil, ExxonMobil] said their dealings in Equatorial Guinea had been proper and lawful...Interest in the land deals grew out of a money-laundering inquiry involving accounts held by Equatorial Guinea at Riggs Bank in Washington. [also refers to Abayak, ChevronTexaco, Devon Energy, Amerada Hess]