'We are at one kidnapping and extortion per week'

Crypto investors go to extraordinary lengths to safeguard their Bitcoin, which exists only as digital records on the blockchain, and is routinely protected by multiple encrypted passwords.

- 

But all it takes is an attacker threatening to bludgeon an investor with a 5lb metal wrench to persuade them to relinquish their passwords and fortunes.

It can be the perfect crime: millions of pounds can be transferred in an instant, anonymously, and often irreversibly.

The funds can be quickly laundered and hidden through various crypto platforms.

"Wrench attacks," as they are called, have occurred in London, Canterbury and Oxfordshire, and are becoming increasingly violent globally, with at least nine victims losing their lives.

They include steel company CEO Anson Que who was kidnapped and murdered in the Philippines in March, even though a £2.6million crypto ransom was paid.

After French crypto firm co-founder David Balland and his wife were abducted in January, his severed finger was sent to his company with the demand for a 10million euros ransom.

In Las Vegas, Nevada, a crypto investor was kidnapped at gunpoint and forced to transfer £3.6million in crypto assets before he was dumped in the desert.