Special counsel Robert Mueller's team accused Paul Manafort, President Donald Trump's former campaign chairman, of "foldering," a technique used by drug cartels and terrorist groups to secretly communicate with witnesses.

The practice of foldering is when two or more people communicate through email drafts, using an email account that all participants have the password to, rather than corresponding through sending email messages.

The technique was originally used by the terrorist group Al Qaeda and was also by David Petraeus when he tried to hide his extramarital affair during his tenure as CIA director, as journalist Yashar Ali noted.

Foldering is a communication technique that has also been used by drug cartels, according to Renato Marrioti. Marrioti said Manafort knew he was doing something wrong and did not want to be caught exchanging messages with witnesses.