A man has been jailed for making bogus bomb detectors that he claimed could find missing Madeleine McCann.

Sam Tree, 68, of Dunstable, Bedfordshire, claimed the dud devices, which he made in his shed, could track down explosives, drugs and people.

Detectives said the sentencing was the “concluding act in a highly complex, extensive and significant investigation” that had seen three other British con artists convicted of making fake detectors.

It is believed the criminals made about £80m from the scam.

Tree was jailed for three-and-a-half years at Kingston crown court, London, on Friday after being found guilty at the Old Bailey in August of making an article for use in a fraud between January 2007 and July 2012.

His wife, Joan Tree, 62, was given a two-year prison sentence suspended for two years and ordered to do 300 hours of unpaid work in the community, after being convicted of the same offence.

The instruction manuals that accompanied their products claimed the user’s static electricity would power the aerial to move if it detected the substance it was searching for. The device could supposedly track down missing people – including, it was claimed, Madeleine McCann – by simply putting a photo of the individual in the box.

In passing sentence, Judge Richard Marks QC told the pair: “The aerial would point to the vicinity or direction of the objects or person being looked at. One only has to look at the facts to see this as a bizarre and fantastic proposition as to be almost akin to something out of Alice in Wonderland.”

The Trees broke down in tears and embraced each other after the hearing.

DC Joanne Law, who led the investigation for the City of London police’s overseas anti-corruption unit, said after the hearing: “It really is just an empty plastic case. It’s wishful thinking and nothing more. It plays on people’s desire to find a very simple solution to a very complex problem.”

She said the detectors and the so-called science behind them were examined by experts who concluded “it’s absolute rubbish, none of it is true”.