The life of a prosecutor targeting public corruption doesn't get any more rewarding than the past few weeks have been for Patrick Fitzgerald, US attorney in Chicago.

On Monday, Mr Fitzgerald filed criminal complaints against two city officials in Chicago, alleging ‘pervasive fraud' at City Hall and charging them with using political patronage to award jobs and faking tests for employees. The arrests marked the first time an 18-month corruption investigation had reached inside Mayor Richard Daley's office.