US-based firm Oakley International was taken on by the Find Madeleine Fund earlier this year on a £500,000 six-month contract.
The company was chosen by double-glazing tycoon Brian Kennedy, who has promised to back the McCanns financially to help solve the mystery of the disappearance of their daughter.
Oakley was hired to monitor a telephone hotline, carry out detective work and review CCTV footage from around the world of possible sightings of the missing girl.
But Mr Kennedy became concerned by the level of Oakley’s £43,500 ($74,155) expenses claim in the first month of the contract.
Madeleine McCann ICMEC poster