Why would Paul Hastings pay $90,000 to Atlanta’s former city attorney after the law firm earned millions representing the city and its airport under her watch?

That’s a key question for federal prosecutors in the ever-widening, almost four-year corruption probe into former Mayor Kasim Reed’s administration. The probe expanded earlier this year to the city’s dealings with Paul Hastings and Reed’s ex-city attorney, Cathy Hampton, the Atlanta Journal-Constitution has reported.