Police have released images showing four suspects wanted in connection with a $195,000 fraud that involved bitcoin ATMs in seven Canadian cities.

The Toronto Police Service says in a news release that the Calgary Police Service received information in October about “multiple fraudulent transactions that had been made across the country, specifically targeting one Canadian bitcoin company.”

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Police say that 112 fraudulent transactions were made between Sept. 16 and Sept. 26. Fifty-one of the transactions occurred in Calgary, with the others in Toronto (17), Montreal (27), Ottawa (1), Hamilton (1), Winnipeg (13) and Sherwood Park, Alta. (2).

Police say the suspects committed “double-spend attacks” in which they withdrew money from a bitcoin kiosk and then remotely cancelled the transactions before the withdrawal was processed.

“All four suspects are described as men and are believed to have in-depth knowledge or interest in cryptocurrency, bitcoin and/or blockchain technology,” according to Toronto police.

Police are asking anyone who can identify the suspects to call the Calgary Police Service at 403-266-1234, regardless of where they live in, or contact Crime Stoppers if they wish to remain anonymous.