A private detective hired to investigate the disappearance of Madeleine McCann before being convicted as a conman has been found dead at his Surrey mansion.

Kevin Halligen, 56, was taken ill last Monday at his Guildford home and subsequently died. Police said they were treating the death as unexplained. There is no suggestion anyone else was involved in his death.

Halligen was employed by Kate and Gerry McCann in 2008 before being fired the following year after it emerged he had squandered much of the £500,000 fee on “pointless tactics”.

He was accused of conning the fund to find Maddie McCann out of £300,000. He featured in the 2014 Channel 5 documentary The McCanns and The Conman, during which he denied spending money from the family fund on first class travel and luxury hotel rooms.