Giuseppe Borsellino, a construction entrepreneur from the Montreal area, occupied the lion's share of the commission's time this week.

Borsellino, the head of Laval-based Garnier Construction, has worked in Montreal since the 1980s and has won public infrastructure contracts worth millions during the years he's been in business.

EVIDENCE FILE: The commission's profile of Giuseppe "Joe" Borsellino.

Borsellino admitted to taking part in a collusion scheme over city of Montreal public works contracts that saw bids rigged in exchange for kickbacks and false extras approved for additional profit. Contrary to earlier testimony from previous witnesses, Borsellino says it was actually former city engineer Gilles Surprenant who initiated the scheme.

Here's what you need to know about Borsellino's testimony:

1.Vague responses

Borsellino was one of the few witnesses who refused to meet with investigators before taking the stand. As a result, the witness gave vague answers when presented with specific evidence for the first time, including wiretapped conversations and phone records.

That led to some tense exchanges between Borsellino, commission prosecutor Simon Tremblay, and commission chair France Charbonneau. Justice Charbonneau frequently stepped in and pressed the witness for answers that went beyond "I don't recall," or "To the best of my memory."

WATCH: Heated exchange over $10,000 donation

IN HIS WORDS: "I think I was invited to one of the weddings. But I’m still not sure. And I knew it coming here, that maybe if we get to that, I wouldn’t be able to confirm. But probably was invited to one wedding. And it’s probably because the bride, I knew the parents of the bride. But I’m still not sure. And I’m not sure if I went. Okay." (On his invitation to the wedding of Vito Rizzuto's son.)

2. Contradictions

The commission heard several examples of what the prosecutor claimed were contradictions between Borsellino's account of events and the evidence collected by law enforcement, previous witnesses, and commission investigators.

That included a $50,000 Italian vacation he said he paid for and organized. The guest list included the former head of FTQ-Construction, Jocelyn Dupuis, and the then-head of the city's public works department, Robert Marcil.

Borsellino claimed that he arranged the trip to improve his company's standing with the city after several of his company's projects were cancelled.

However, the prosecutor suggested that the trip was more closely linked to one particular contract than Borsellino's overall reputation with the city. The final approval for a $5 million emergency infrastructure project was signed by Marcil just two weeks after the Italian vacation reservations were finalized.

Tremblay proposed the trip was actually compensation for the contract. Borsellino denied that claim.

IN HIS WORDS: "Sir, yes. I'm telling you that [Marcil] signed, I never saw this letter. I might have seen it now, okay. It's not something that I look at the date. The work was done way before, the position was taken way before, and it had nothing to do, absolutely nothing. And it's twice you mention I'm, you know, I'm under oath, and I understand that. And that's why I could answer comfortably that it had nothing to do [with it.]"

3. Links to powerful people

Borsellino admitted to having friends in powerful places, but denies using those relationships for his own financially benefit or that of his company.

Those relationships include:

Former Liberal MNA Tony Tomassi: Borsellino said Tomassi was a friend before he was appointed family minister. In a recorded conversation played before the inquiry, Borsellino describes partying with the MNA for three days after he was appointed to Jean Charest's cabinet in 2008. The witness said he was happy for his friend's success and nothing more. Tomassi resigned his MNA post last year after he was charged with fraud and breach of trust.

LISTEN: Borsellino's recorded conversation on Tomassi [in French]

Jocelyn Dupuis, former head of FTQ-Construction: Borsellino said he had been friends with Dupuis for years and called to consult with him on projects after Dupuis resigned from the union federation's construction arm in 2008. Recorded conversations showed they discussed at least two projects: A Club Med renovation in Florida and a land deal in Montreal. Dupuis was later charged with fraud in connection with expenses claimed to the union. He has pleaded not guilty to those charges.

The Rizzuto clan: Borsellino denied having a close relationship with members of the Rizzuto family, who reportedly held the top positions in the Montreal Mafia. His parents come from the same small village in Sicily, Cattolica Eraclea, where the Rizzutos trace their roots. He denied attending any Rizzuto family events, but said he may have been invited to one wedding, through the bride's side. Borsellino could not confirm either the invitation or his attendance for the commission.

IN HIS WORDS: (On the infiltration of organized crime in the construction industry)

"Mr. Tremblay, for me, since I've been in business, I've tried to keep my business with my people, as close as possible. So meaning that if I know that there is businesses that are infiltrated, if I... If I know, I wouldn’t work with them. But that’s only assumptions. I cannot say, and I said this before, I can’t say that including any business, if it’s infiltrated or not. I don’t know."

4. Violence and intimidation in the industry

Borsellino referred to it as "my accident," but the 2009 incident was actually a beating that left Borsellino so severely injured, he required seven hours of facial reconstruction surgery. While he would not conclusively link the motive to his work in the industry, Borsellino implied that it might have been connected to a job he had done or outstanding debts. He did not report the beating to police.

Borsellino also denied playing a role in intimidating another contractor, Michel Leclerc, who previously testified before the commission, and said Borsellino tried to scare him off a bid by calling and threatening him.

WATCH: Michel Leclerc was threatened, inquiry hears

IN HIS WORDS: "Moi, l’histoire it’s a bit distorted but, you know, a little bit distorted, I’ll tell you my version of the facts.. . The fact was it’s true I called [Leclerc] . And I wanted him to put a bid "de complaisance" or not,whatever, and I didn’t look for him and it’s true I placed a truck there just to see if they were putting in the bid but there was no intimidation. And I knew he was putting in the bid and I didn’t harass him."

WATCH: Borsellino on intimidation allegations

5. Political donations

Borsellino made donations to the three major provincial political parties, but insisted those donations were all above board. They came primarily in the form of tickets to cocktails which Borsellino said he attended to raise the profile of his company and to network.

He told the commission that he was actively solicited to attend the events by party fundraisers, who pitched them as a networking opportunity. Borsellino said he eventually stopped attending the events, because he deemed the donations 'unethical.'

He also admitted to writing a $10,000 company cheque, which was handed over to Union Montréal organizer Martin Dumont. Borsellino was vague about his intentions for that donation, but suggested it was to support the de-amalgamation campaign.

Political donations made by Giuseppe Borsellino and his family as reported to the Quebec's director general of elections. (Charbonneau commission)