Anti-corruption officers on Friday detained a former Mexican politician at Madrid’s airport.

Humberto Moreira, former chief of the Institutional Revolutionary Party, was served a Spanish arrest warrant and held in custody. It is still not fully known why he was sought by officers, Wall Street Journal wrote.

According to the US Department of State records, in 2012, Moreira resigned as party leader amidst state government debt that continued to grow up to $2.5 billion while he was governor of Coahuila from 2005 to 2011. The debt was partly financed by falsified documents. He has no charges in Mexico or the United States.

Two of Moreira’s top associates already pleaded guilty to conspiring to transport stolen money in a federal court in San Antonio, Texas. In the plea agreement for Roland Gonzalez Trevino, Moreira appeared to be the unnamed co-conspirator, described as a high-ranking Coahuila official who won the governorship, Business Insider reported.

According to the document, he took money from the government of Coahuila for his personal use. Gonzalez admitted that he joined a plan to defraud or steal money from Coahuila with the unnamed co-conspirator and others, as well as transferring over $1.8 million, which was stolen or taken by fraud from the state of Coahuila and forwarded to the US.

In 2014, Hector Javier Villareal Hernandez pleaded guilty to conspiracy to launder money as well as conspiring to transport stolen money.

Spanish judge Jose de la Mata stated the conversations with Moreira, who explained how the funds originated from the regular operations of two of his companies in Mexico, were insufficient. De la Mata ordered Moreira’s detention, Wall Street Journal also revealed.

Kent Schaffer, the attorney representing Moreira, stated that he was aware of his client’s detention but did not provide details. A lawyer for Moreira also previously requested that he be set free with or without posting bail. However, the judge denied the request due to Moreira’s resources.

“In this particular case, the risk (that Mr. Moreira may flee Spain) is particularly acute because of the financial and other resources, as well as connections with other parties, that the suspect has available if he were to move overseas and avoid the reach of Spanish justice,” said De la Mata.

The judge added that he will forward the case to another Spanish judge, who will decide whether Moreira should stay behind bars.