He said use of the equipment, which scrambles plain text into unbreakable code, is skyrocketing among organized crime groups.

CNN: Officials warn of 'electronic sanctuary' for criminals

In Mary's case, Elizabeth's master code breaker Thomas Phelippes cracked the cipher and exposed her crime.

FORBES: I've got a secret

The methods they used to avoid detection were straight out of a crime novel - they wrote cryptic notes using numbers and letters and spoke in code on the phone.

BBC: Operation Beath