4 MIN. DE LECTURA
June 23 (Reuters) - Prosecutors and federal police in Brazil unearthed the country's largest-ever corruption scandal by tying a ring of black-market money changers to a price-fixing and political kickback scheme at state-run oil firm Petrobras .
Executives from two dozen top engineering firms are accused of inflating the value of service contracts and funneling the excess funds into their own bank accounts and to political parties, including President Dilma Rousseff's Workers' Party.
The investigation is likely to continue for at least two more years and may widen to include the country's biggest electric utility, Eletrobras, a lead prosecutor on the case told Reuters on Tuesday.
Here are some key moments of the investigation, which has ensnared Brazil's most powerful executives and politicians:
March 20, 2014
Federal police arrest the former head of Petrobras' refining and supply department Paulo Roberto Costa, the result of an investigation that started when they noticed Costa had been given a Range Rover by convicted money changer Alberto Youssef.
Aug 22, 2014
Costa signs a plea bargain deal with prosecutors, agreeing to explain the corruption scheme and name beneficiaries in exchange for a lighter sentence. Plea bargain deals become a cornerstone of the investigation.
Nov 14, 2014
Federal police arrest 18 people including former Petrobras engineering and services director Renato Duque and senior engineering executives, the first broad raid of the investigation.
Dec 11, 2014
Prosecutors in Curitiba formally charge 36 people, 22 of them from engineering firms OAS , Camargo Correa, UTC Engenharia, Galvao Engenharia, Mendes Junior and Engevix. Prosecutor Deltan Dallagnol declares war on corruption in Brazil in a nationally televised press conference.
Dec 29, 2014
Petrobras bans 23 suppliers cited in investigation from bidding in future tenders.
Aldir Bendine, former head of state-run Banco do Brasil SA, steps in as Petrobras CEO after Maria das Graças Foster and other senior leaders abruptly resign.
Brazilian prosecutors file lawsuits against six construction and engineering groups, seeking over $1 billion in damages related to contract fixing, bribery and political kickbacks.
Brazil's Supreme Court says it will investigate the speakers of both houses of Congress and 32 other sitting politicians in connection with the Petrobras scheme. Twelve senators and 22 congressmen from five parties are under investigation, all but one from President Rousseff's governing coalition.
Brazilian police arrest the treasurer of the ruling Workers' Party, Joao Vaccari, moving the investigation closer to President Rousseff's inner circle. Vaccari resigns to focus on his defense.
Paulo Roberto Costa is sentenced to 7 years and 6 months in prison, but will only serve one year of house arrest due to his collaboration and time already spent in detention. A total of eight people are convicted in the first sentences of the investigation.
After lawyers fiercely contest the legality of lengthy pre-trial jailings in Curitiba, the Supreme Court overrules federal judge Sergio Moro and orders nine executives to be released on house arrest.
Nestor Cervero, former international director of Petrobras, is sentenced to five years in jail for money laundering.
Brazilian police arrest the chief executives of the country's two largest construction companies, Marcelo Odebrecht, head of family-run conglomerate Odebrecht SA, and Otavio Marques Azevedo, CEO of Andrade Gutierrez. Prosecutors say the companies led the cartel of engineering firms. (Reporting by Caroline Stauffer; Editing by Christian Plumb)