WASHINGTON -- Since the fall, senior aides to Timothy Geithner have closely dealt with American International Group Inc. on compensation issues including bonuses, both from his time as president of the Federal Reserve Bank of New York and as Treasury secretary.

The extent of their involvement, which wasn't widely known, raises fresh questions about whether Mr. Geithner could have known earlier about AIG's $165 million in bonus payments. When the bonuses sparked a political firestorm last week, Mr. Geithner said he learned...