A man who held several roles in the Harper government has testified about bizarre financial dealings he witnessed in his previous career in Montreal municipal politics — like the safe so stuffed with cash it wouldn't close.

Martin Dumont, who worked as a policy adviser in the office of Prime Minister Stephen Harper and as a senior aide for cabinet ministers Diane Ablonczy, Jim Prentice and Josée Verner from 2007 to 2010, testified at Quebec's public inquiry into corruption in the construction industry Monday.

He shared memories of his earlier days in municipal politics, when he worked for the party of Mayor Gerald Tremblay, before he left for Ottawa.   

Dumont recalled his frustration at witnessing abnormally high prices on public works contracts and said that, when he began inquiring into them, he was told by civil servants to stop asking so many questions.   

He remembered working at a political fundraiser where the mayor's party got large, but legal, donation cheques from members of the construction industry — including one with extensive ties to the most powerful figures in the Mafia.

He also shared vivid memories of the man known as "Mr. Three Per Cent" -- Bernard Trepanier, the partisan fundraising official accused of collecting kickbacks from construction companies on behalf of the mayor's Union Montreal party.

Trepanier faces criminal charges, including fraud, but none of the allegations against him have been proven in court.  

Dumont said Trepanier frequently shut the blinds and door when meeting people in his office. He said he was once called in because Trepanier had a problem: he couldn't close the door to a safe in the office, because it was just too full.   

"It was the most money I've ever seen in my life," Dumont said. "I was pretty shocked... I expected to see fives, 10s and 20s (in bills gathered from fundraising events)."

An inquiry lawyer asked him what denominations he saw instead.

Dumont said he remembered the colours of the bills -- an array of tones usually associated with far larger denominations, ranging from $50 to $1,000: "What I remember is the colours: Red, brown, pink."   

He said he and Trepanier, pooling their strength, managed to force the safe closed together. He said he joked with Trepanier afterward that he might want to consider getting a bigger safe.   

Dumont testified that, to his surprise, a few days later there actually was a bigger safe in the room, located in the offices of the Union Montreal party.

'Call me Mr. Sidewalk,' Milioto told Dumont

He also described a memorable encounter with Niccolo Milioto.   

Milioto is a construction boss seen, on decade-old police surveillance video, repeatedly exchanging cash with the top figures in the Rizzuto crime family. He has been described during inquiry testimony as a middleman between the construction industry, the Mob, and the mayor's party.   

"(Milioto) said, 'You can call me Mr. Sidewalk,"' Dumont testified. "I think I butchered his family name. So he told me, 'Don't worry about it, just call me Mr.. Sidewalk."'

That was in 2004, well before Dumont went to work in Ottawa. The ongoing Quebec probe is not exploring the fundraising of federal political parties.