A former acting director of the Central Intelligence Agency (CIA) Michael Morell believes the already limited use of Bitcoin in illicit activity is on the decline. In a letter published by global security publication The Cipher Brief, Morell says there is "mounting evidence" showing a "shift" by illicit users "from Bitcoin to cryptocurrencies with stronger anonymity" such as the Anonymity-Enhanced Cryptocurrencies (AECs). The former CIA director says online darknet marketplace (DNM) White House Market and ransomware-as-a-service group Sodinokibi are now only accepting privacy-focused cryptocurrencies for payments. "The prominent DNM 'White House Market' has moved to accepting Monero (XMR) exclusively. Similarly, the ransomware group, Sodinokibi, no longer accepts Bitcoin as payment and will only take Monero." According to Morell, Bitcoin's publicly available and verifiable blockchain makes it ill-suited for criminal activity.

"In fact, its transparent nature led one blockchain analytics expert to compare transactions on blockchain to having the 'whole world' be a witness to paying someone $2,000 in a dark alley. Based on our research, I have come to believe that if there was one financial ecosystem for bad actors to use that would maximize law enforcement's chances of identifying them and their illicit activities, it would be blockchain."