Money laundering accounts for up to 5% of global GDP - or $2tn (£1.5tn) - every year, says the United Nations Office on Drugs and Crime. So banks and law enforcement agencies are turning to artificial intelligence (AI) to help combat the growing problem. Money laundering, so-called after gangster Al Capone's practice of hiding criminal proceeds in cash-only laundromats in the 1920s, is a huge and growing problem. "Dirty" money is "cleaned" by passing it through layers of seemingly legitimate banks and businesses and using it to buy properties, businesses, expensive cars, works of art - anything that can be sold on for new cash. And one of the ways criminals do this is called "smurfing".