Mexico rocked by claims of corruption against three former presidents

Leaked deposition by recently extradited former head of state oil company Pemex alleges staggering scale of high-level corruption

Mexico's political establishment has been shaken by claims that three former Mexican presidents and an all-star cast of lawmakers and aides may have been involved in alleged acts of corruption.

The accusations were leveled by Emilio Lozoya, the former head of Mexico's state oil company Pemex, and will boost efforts by the country's current president, Andres Manuel Lopez Obrador, to portray himself as an anti-corruption crusader.