The handling of the accounts might have been comical if a nation’s wealth hadn’t been at stake; the manner of deposits was, on occasion, Chaplinesque. The Riggs official who managed the accounts from the bank’s DuPont Circle branch, Simon Kareri, twice went to the Equatoguinean Embassy, a mile away on 16th Street, and picked up suitcases that, as detailed in the Senate report, weighed 60 pounds and contained $3 million in plastic-wrapped stacks of $100 bills. He ferried them back to Riggs and deposited them into one of Obiang’s accounts. The bank also received cash deposits of more than $1.4 million into accounts belonging to Constancia Nsue, one of Obiang’s wives. In those cases — as with other cash deposits that larded accounts controlled by Obiang and Nsue — Riggs did not file “Suspicious Activity Reports” to the OCC as required whenever a bank suspects, or should suspect, that a transaction might involve illicit funds or the laundering of illicit funds.

(The oil account, as well as the others, was closed after the Senate investigation began, and Obiang’s government says that the funds are currently deposited at the Bank of Central African States, a regional institution based in Cameroon that holds treasury accounts.)The committee reported a litany of other unorthodox activity. Riggs helped Obiang set up Otong S.A., an offshore shell corporation in the Bahamas to which he deposited $11.5 million in cash. Reporting these transactions to U.S. officials, Riggs “repeatedly mischaracterized” Otong as a “timber export company.” Riggs also issued a $3.75 million loan to Obiang’s eldest son, Teodoro Nguema Obiang, to purchase a penthouse apartment in California. (Teodoro, owner of a fleet of Ferraris, Lamborghinis, and Bentleys, started a rap label in Beverly Hills.) But not all of the transactions were to Obiang’s benefit: The bank “exercised such lax oversight” over Kareri, the manager of the Equatoguinean accounts, that he was able to “transfer more than $1 million in E.G. oil revenues to an account he controlled at another bank.”

As the Senate report concluded, “Riggs Bank serviced the E.G. accounts with little or no attention to the bank’s anti-money-laundering obligations, turned a blind eye to evidence suggesting the bank was handling the proceeds of foreign corruption, and allowed numerous suspicious transactions to take place without notifying law enforcement.” Riggs officials declined to comment for this story.The committee’s rebuke did not end with Riggs. “Oil companies operating in Equatorial Guinea,” Senate investigators wrote, “may have contributed to corrupt practices in that country by making substantial payments to, or entering into business ventures with, individual E.G. officials, their family members, or entities they control, with minimal public disclosure of their actions.” Those conclusions triggered the current inquiry by the SEC into oil company transactions. Although the SEC won’t comment on ongoing investigations, it is understood to be probing possible violations of the Foreign Corrupt Practices Act, which prohibits American companies from making direct or indirect bribes. (The oil companies deny wrongdoing and say they are cooperating with the SEC.)