The investigation into the expenses of Lancashire’s police chief cost more than five times the amount he was accused of claiming fraudulently.
Police and Crime Commissioner Clive Grunshaw said it was “difficult to justify” spending around £8,000 on the probe, sparked by allegations he had fiddled his expenses.
The Crown Prosecution Service (CPS) announced no charges would be brought against Mr Grunshaw after a three-month investigation.
Figures show a team of four experts spent a total of 117.6 hours - more than 15 full working days - painstakingly sifting through 452 claims made by Mr Grunshaw over a three-year period while he was county councillor for Fleetwood.
They found no evidence he acted dishonestly but identified 37 claims, thought to be worth around £1,550, that may have been submitted incorrectly.