A Spanish court ruled Thursday that a former head of Mexico’s state oil company must remain in custody while an extradition case is heard against him.

A judge ruled that Emilio Lozoya is a flight risk, according to a statement from the National Court in Madrid.

Mexico issued international arrest warrants against Lozoya last year as a result of corruption investigations. Lozoya has denied wrongdoing.

When he was arrested Wednesday in the southeastern Spanish port of Malaga, Lozoya had a driving license bearing his photograph but a different name, according to the court statement. The judge took that as an attempt to evade justice.

Spanish authorities said Lozoya had entered Spain two days earlier, but a search had been on for him throughout Europe since May.

He is one of the most high-profile detentions for alleged corruption under Mexico’s current president, President Andrés Manuel López Obrador, who has vowed to crack down on graft.

Lozoya was the director of Pemex between 2012 and 2016, during the administration of former President Enrique Peña Nieto. He had also been a key member of Peña Nieto’s presidential campaign.

Last year, López Obrador’s administration issued a number of orders for his arrest. One tied him to the bribery scandal of Brazilian construction behemoth Odebrecht and another to the sale of a fertilizer plant to Pemex at allegedly inflated prices.