A police department in Midlothian, in the suburbs of Chicago, had to pay $606 in bitcoins to criminals to get back access to data on their computer, Chicago Tribune reports.

In January, someone at the department opened a virus sent via email, which locked down all data on one of the police computers. A message appeared requesting a ransom in bitcoins to be sent to the hackers in exchange for instructions on how to unblock the computer.

Midlothian Police Chief Harold Kaufman refused to comment on the situation although admitted that the police department had been hacked. Chicago Tribune has requested records from the police and found that $606 were transferred from the village funds to a bitcoin cafe in New York. The transaction was labelled "for MPD virus". The payment included transaction fees. The cafe forwarded the money to the hacker’s wallet.

The hacker did not access any of the information but only locked access to it. The virus was called "Cryptoware", according to Calvin Harden Jr., Midlothian's IT vendor.

"Because the backups were also infected, the option was to pay the hacker and get the files unencrypted," Harden said, "which is what we decided to do.”

In November 2014, the sheriff's office in Tennessee paid $572 in bitcoins to a hacker known as Nimrod Gruber to regain access to its files. The computer was attacked by malicious software called "CryptoWall" and the data were encrypted similarly to the Chicago case. Experts from Pentagon and FBI were not able to unblock the computer, according to reports.

In the Tennessee incident, a large part of the data was restored but 72,000 files remained affected on the host computer, including sensitive data related to ongoing investigations, to current and past prosecutions, and other non-replaceable documents.

Co-chair of the Communications and Technology Committee for the Illinois Association of Chiefs of Police, Mike Alsup, said

 “Hardly a day goes by that we don’t see in both the print and audio media, we hear of instances of computer crime, computer hacking, large organized criminal groups internationally that are stealing through the use of computers.”