The Bulgarian police seized hundreds of thousands of units of Bitcoin in May back when no one anticipated the value to surge by 600 percent.

Axar.az reports citing sputniknews.com

In an anti-corruption purge back in May, Bulgarian authorities seized 213,519 Bitcoins, at the time worth $500 million. Now their value is a staggering $3.6 billion.

Bulgarian law enforcement, together with the Southeast European Law Enforcement Center (SELEC), a regional organization comprised of 12 member states, worked together to bring down a sophisticated organized crime network in May.
The operation involved a large-scale hunt for more than 100 addresses, suspects, and vehicles. Out of the 23 Bulgarian suspects arrested, five were customs officers.

The transactions can be made anonymously, making the currency popular with criminals.

Bitcoin has seen an exponential rise in value this year, from just below $1,000 at the beginning of the year to over $18,000 on December 7.