A former executive of Berkshire Hathaway’s General Re faces sentencing for his role in an accounting scandal that cost shareholders of insurer American International Group more than $500 million. Richard Napier will be sentenced Tuesday in federal court in Hartford. Napier pleaded guilty in 2005 to conspiracy to commit securities fraud, reports the Associated Press. Napier became an important government witness in the case, which led to the convictions of five top executives. Prosecutors said AIG paid Stamford-based Gen Re in a secret deal to take out reinsurance policies with AIG. They said the bogus deal made it look like Gen Re was going to pay AIG $500 million in premiums, when in reality Gen Re would pay no premiums and actually receive $5 million from AIG.