The mystery that surrounded the sudden and unexplained departure of Lester Crawford shortly after his confirmation as FDA chief has cleared up. Crawford was charged yesterday with lying about the stocks he owned in companies regulated by the agency. Specifically, Crawford owned stock in Pepsi and Sysco at a time he chaired the FDA's Obesity Working Group, which made decisions about snack and soft drink products. And he had owned stock and been a member of the board of Embrex, an agricultural biotech company regulated by the FDA. The criminal charges brought by the Justice Department allege that Crawford lied about the shares, saying they had been sold. Crawford's attorney says he will plead guilty today to two misdemeanors: false writing and conflict of interest. Each charge carries a potential one-year jail sentence.