Criminals now prefer Monero over Bitcoin because Bitcoin can be traced.

Bloomberg reports the Criminal Underworld Is Dropping Bitcoin.

Bitcoin is losing its luster with some of its earliest and most avid fans — criminals — giving rise to a new breed of virtual currency.

Privacy coins such as monero, designed to avoid tracking, have climbed faster over the past two months as law enforcers adopt software tools to monitor people using bitcoin. A slew of analytic firms such as Chainalysis are getting better at flagging digital hoards linked to crime or money laundering, alerting exchanges and preventing conversion into traditional cash.

The European Union’s law-enforcement agency, Europol, raised alarms three months ago, writing in a report that “other cryptocurrencies such as monero, ethereum and Zcash are gaining popularity within the digital underground.” Online extortionists, who use ransomware to lock victims’ computers until they fork over a payment, have begun demanding those currencies instead. On Dec. 18 hackers attacked up to 190,000 WordPress sites per hour to get them to produce monero, according to security company Wordfence.

For ransomware attacks, monero is now “one of the favorites, if not the favorite,” Matt Suiche, founder of Dubai-based security firm Comae Technologies, said in a phone interview.

In monero’s case, criminals are snapping it up because bitcoin’s underlying technology can work against them. Called blockchain, the digital ledger meticulously records which addresses send and receive transactions, including the exact time and amount — great data to use as evidence. Match an address to a crime and then watch the bitcoin universe carefully, and you can see the funds disappear and reappear in other locations.

Started in 2014, monero is very different. It encrypts the recipient’s address on its blockchain and generates fake addresses to obscure the real sender. It also obscures the amount of the transaction.

The techniques are so potent that software that flags coins suspected of being obtained through crime now tags just about anything converted into or out >of monero as high risk, according to Pawel Kuskowski, chief executive officer of Coinfirm, which helps exchanges and other companies avoid tainted money. That compares with only about 10 percent of bitcoin, he said.