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.