He was a soldier within the Pegorino crime family. He, along with Peter Marchetti and Niko Bellic, acted as bodyguards for Don Jimmy Pegorino when he went to meet with members of the Pavano crime family during the mission "Pegorino's Pride".
Upon arriving at the DUDE Chemicals plant in Acter Industrial Park, Big Pete and Marco accompany Pegorino to the meeting point while Niko watches from a building. After a short wait, Pavano hitmen assault the trio; Pegorino is wounded, but survives while Big Pete and Marco are, unfortunately, killed.
- GTA IV
- Pegorino's Pride (Killed)
- Big Pete and Marco are both incredibly fond of Pegorino, complimenting him and practically hero worshiping him, even when Pegorino is verbally abusive towards them. After their deaths, Pegorino shows some remorse for having been cruel to them in their last moments, but states that one has to get used to losing men in the Mafia.
- Marco Bonnaro's surname sounds similar to former real-life mafioso Joseph Bonanno, former head of the Bonnano family