E-mails have become the Holy Grail for investigators and prosecutors working to unearth criminal culpability in questionable financial behavior, providing smoking gun evidence of possible wrongdoing.

The latest target in this line of inquiry is American International Group, as government investigators try to figure out whether key executives were simply inept when they allowed the company to nearly go bankrupt, or perpetrated criminal fraud by deceiving investors.

The longtime bane of the insurance industry, Eliot Spitzer (New York's former attorney general and governor), along with Frank Partnoy (professor of law at the University of San Diego) and William Black (a professor of economics at the University of Missouri-Kansas City) wrote an op-ed column in The New York Times on Dec. 20 demanding that investigators thoroughly examine the e-mail exchanges between executives before allowing AIG to pay off its loans and release itself from the government's leash.