But at the trial of former American International Group CEO Hank Greenberg, Quince's name emerged in an email sent during the height of the crisis.

Edward Quince. Aka: Ben Bernanke, the former chairman of the U.S. Federal Reserve.

Lawyers during the trial identified Quince as Bernanke in the email.

The Wall Street Journal, which earlier on Friday reported Bernanke's alias, said the Fed's general counsel testified that the former Fed chairman used the name during the financial crisis to make sure he did not receive extraneous emails. It is not clear what was meant by extraneous emails.

A Fed representative confirmed that the name was used as a pseudonym by Bernanke for the email.

Bernanke took the stand on Thursday to defend the U.S. government's bailout of AIG, describing how policymakers sought to avoid giving AIG shareholders a "windfall" through a rescue.

The lawsuit, which is being tried in the Court of Federal Claims in Washington, won class action status in May 2013.

The case is Starr International Co v. U.S., U.S. Court of Federal Claims, No. 11-00779.

Bernanke's testimony is expected to continue on Friday, but whether he explains what lay behind the Quince identity remains to be seen.

(Reporting by Michael Flaherty and Aruna Viswanatha in Washington; editing by Matthew Lewis)