The Charbonneau commission looking into corruption in Quebec's construction industry has heard its final witness until the fall.

Jacques Duchesneau, former head of the province's anti-collusion unit, appeared before the Charbonneau Commission once again on Thursday.

During his questioning, government lawyer Benoît Boucher inquired exclusively about Duchesneau's hiring and working conditions at the unit.

Duchesneau made headlines during Quebec's corruption inquiry when he claimed that provincial political parties have raised 70 per cent of their cash illegally.

He said he was there to discuss matters of corruption and not his working conditions.

On Wednesday, Duchesneau, and two ex-colleagues also on the witness stand, were being grilled over the evidence to back up their bold assertions.

The questioning became so fierce at one point that the presiding judge cautioned other lawyers to avoid aggressive cross-examinations.

Duchesneau even fielded tough questions from a lawyer for the Parti Québécois, which has been accusing the governing Liberals of corruption for months.

The party wanted to know why Duchesneau had taken it upon himself to continue his investigation into political corruption after he had been relieved of his duties as the leader of an anti-collusion unit.

Hearings will restart on Sept. 17.

With files from the Canadian Press