The initial hearing into corruption charges against the former CEO of the Mexican state run petroleum company known as PEMEX, Emilio Lozoya Austin, is set for Tuesday.
Lozoya will appear before the judge via video-conference from a hospital where he has been since he was extradited from Spain last Friday.
He was said to be in poor health when he arrived back in Mexico.
Lozoya, who headed Pemex from 2012 to 2016 under Mexico's former president, Enrique Pena Nieto, is denying charges he took bribes and was involved in money laundering.
Prosecutors say Lozoya asked for and obtained $4 million from Brazilian company Odebrecht, and then moved the cash into the coffers of Nieto's 2012 election campaign and diverted some of the money for his personal use.