MONTREAL—For the second time in as many days, investigators working for the Surete du Quebec’s anti-corruption squad raided a property owned by Laval mayor Gilles Vaillancourt.

At suppertime, SQ officers entered the mayor’s two-storey condo on Cageux St. A day earlier, they raided the mayor’s city hall office and his home.

The raid came only hours after an indignant Vaillancourt refused to step down from the position he has held for 23 years.

The SQ’s “Hammer Squad” has been operating since 2009, looking for clues of corruption and other economic crimes in the way that the province and municipal governments operate.

Vaillancourt has been under heavy scrutiny for some time. The mayor has faced allegations that he gave the Parti Quebec envelopes stuffed with cash during the 1994 election and that he gave public contracts to friends and family members.

Perhaps most damning, reports surfaced this week that nearly a quarter of Laval’s construction contracts over the past decade went to firms owned by Tony Accurso. One of Quebec’s richest men, Accurso has been arrested by both the SQ and RCMP and his offices were again raided this week.