LONDON, ONT. -- An 83-year-old St. Thomas man is out $27,000 following an online scam, police say.

Police believe the man’s computer was infected with ransomware after he either opened a bad attachment or clicked a link that was received via e-mail.

They say the suspects used malware to freeze the man’s computer and then pose as his anti-virus provider to offer him a refund.

The man provided his banking info and then the suspects claimed to have made a mistake and refunded “an exorbitant amount of money,” police say.

The man was then told he needed to return the refund in the form of cash. He was instructed to withdraw three separate amounts of money and courier the cash to an address in Newfoundland.

According to police, the man obliged and then discovered the refund already withdrawn after he sent the cash.

St. Thomas detectives are continuing to investigate.