In an effort to potentially view conversations between witnesses linked to President Trump and Russia, sources told CNBC that since as early as April, Mueller's team has been asking witnesses in the Russia probe to turn over phones for agents to examine private conversations on WhatsApp, Confide, Signal and Dust.

According to the same source, the 'request' worked as, the witnesses - fearing a subpoena - have willingly handed over their phones.

CNBC ends with the usual caveat that nothing has been found, no leaks of anything has been found, but they remain "convinced" that there must be something there...

While it's unclear what Mueller has discovered, if anything, through this new request,investigators seem to be convinced that the apps could be a key to exposing conversations that weren't previously disclosed to them.

Fishing expedition, indeed.