More than two years after the suicide death of White House aide Vincent Foster, Sen. Alphonse D'Amato, chairman of the House Banking Committee investigating the Whitewater affair, said today he will probe explosive allegations concerning how and where Foster died. On Wednesday, FBI agents once again searched the Ft. Marcy park area where Foster's body was found by park rangers, looking again for the bullet that killed him. D'Amato told CBS Radio that he will subpoena a White House employee who told friends in Arkansas that Foster shot himself in his car, on the White House grounds. Foster's body was found several miles away in the park. The White House employee, reports TIME's Suneel Rataan, is Helen Dickey, who was then Chelsea Clinton's babysitter. The White House has offered D'Amato a sworn statement from Dickey in which she describes learning of Foster's suicide late that night and discussing it with a state trooper at the Governor's mansion in Arkansas. Deputy Whitewater prosecutor John Bates said today that the investigation of Foster's death continues.