MONTREAL -- 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 Josee Verner from 2007 to 2010, testified at Quebec's public inquiry 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.

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.

But it has heard a torrent of allegations about wrongdoing at the municipal level -- and there were many more allegations on Monday.

The inquiry heard that the City of Montreal's second most-powerful politician, after the mayor, was among a number of corrupt municipal officials.

A witness from the construction industry said Monday that Frank Zampino, who was once the No. 2 at city hall and the right-hand man to Tremblay, was on the take.

Zampino, the former head of the city's executive committee, has left politics. He was arrested earlier this year and now faces fraud charges.

The testimony against was delivered earlier Monday by Elio Pagliarulo -- a former construction-industry insider who said he ran a loansharking business in partnership with construction magnate Paolo Catania.

Pagliarulo said he personally delivered $300,000 in cash through a middleman, Catania, and the money was destined for Zampino. He said the payments were delivered in three installments of $100,000 and that he saw Zampino one of the times he brought Catania the cash, around 2006.

"I took (the cash) from my personal account," Pagliarulo testified. "I knew in advance that these particular numbers were for Mr. Zampino."

He said he was also aware of $200,000 in renovations done to Zampino's home -- specifically to his kitchen. Pagliarulo was testifying about the corruption, Mafia ties and bid-rigging he witnessed and participated in during his days working with the Catania construction empire.

He said he had a spectacular falling out with his old friends several years ago. He said he owed them money after a business deal went wrong.

He said he was kidnapped for three hours and beaten up. He said his teeth and face were so badly damaged that he needed facial-reconstruction surgery.

He told the inquiry that funeral flowers were also sent to his family home, as a message: pay, or else.

It wasn't the first time he'd witnessed a violent attitude in the industry. He said that when he was on better terms with the Catanias, they discussed the possibility of torching a rival company's vehicles.

As for corruption, Pagliarulo said bribes were rampant and in one case it consisted of paying down the mortage on the house of a municipal engineer.

An inquiry lawyer asked Pagliarulo how far the Catanias would go to maintain their position in the construction industry.

Pagliarulo referred to his own kidnapping and beating.

"If I was his best friend at the time, and look what he did to me, you can just imagine what he'd do to a stranger," he said.

"In the community, you don't mess around with these two people," he said, referring to the father and son team that built the business. "They're connected to a crime family."

He also described lavish parties thrown by his old associates -- including a birthday party he says was attended by Gloria Gaynor, best known for the disco hit, "I Will Survive."