Pierre Lavallée gave up his post as president of the Quebec City-based engineering firm BPR today.
Lavallée appeared as a witness before the Charbonneau commission last week, admitting his firm handed over cash to Union Montréal's former fundraiser Bernard Trépanier in order to secure public works contracts.
He said paying a commission to the man known as "Mr. Three Per Cent" was the only way to get a foothold in the Montreal market.
Lavallée called the practice "shameful," but admitted turning over cash to Trépanier in 2007 and 2008.
Trépanier appeared before the commission for a first day of testimony today.
A string of resignations
Lavallée's resignation comes less than a day after Robert Marcil, the one-time director of public works for the City of Montreal resigned from his post as a senior executive with the engineering firm SM International
Earlier yesterday, Rosaire Sauriol quit his job as vice-president of Dessau, the engineering firm founded by his father.