Police in Toronto say four people are facing charges after a mortgage fraud investigation lasting nearly five years.

Four men between the ages of 45 and 53 are due in court Tuesday on charges including fraud, conspiracy, forgery and money laundering.

Police allege the men, who are all from the Toronto area, took part in a “sophisticated and complex” scheme involving “several high-end properties.”

They estimate the value of the alleged fraud at $17 million.

According to a statement from Toronto police, officers with the force’s financial crimes unit began investigating the alleged fraud in the spring of 2013.