A Mexican senator is demanding that the country’s federal government look into whether U.S. presidential candidate Donald Trump legally traveled to Mexico  in August 2016.

Luis Humberto Fernández Fuentes, who is with Mexico’s Partido de la Revolución Democrática (Party of the Democratic Revolution, or PRD), says that Trump’s lightning-turnaround trip to Mexico City to meet with President Enrique Peña Nieto before traveling back to the United States, all on 31 August 2016, may have violated Mexico’s immigration laws by entering the country without the proper documentation

Senator Fernández Fuentes explained that Article 37 of the Migration Act provides that in order for aliens to enter the country, they must be submitted through an immigration filter before the INM [the National Institute for Migration] and submit their documents — in this case a passport, since U.S. citizens do not require a visa for a stay of less than 180 days in our country.

He said that in the case of Trump’s visit, it is important to clarify whether the Republican bypassed Mexico’s mandatory migratory filters or if he was given a waiver to land his private plane at the presidential hangar, and if so, in what capacity:

The Federal Government has made it clear that the invitation to Mr. Donald Trump was as a presidential candidate. Given these circumstances and the urgency of the invitation, Mexicans ask:

If his entry into the country was properly reviewed and registered by the immigration authorities, complying with the requirements set out in Articles 37 and 40 of the Migration Act and Article 59 of the Rules?

What was the immigration status with which he entered the country, in accordance with Article 52 of the Migration Act?

If necessary, to clarify whether there was a special dispensation to enter the country; under what argument was it granted, and who authorized it?

According to Article 85 of the Migration Act and Article 69 of its Rules of Procedure, the immigration authorities only have leave to inspect the official aircraft of foreign governments and their crews and passengers who enjoy immunities in accordance with the laws and international treaties to which Mexico is a party.

Given the importance of this issue, it is important that each of the above questions be answered in a timely and transparent manner.

Donald Trump’s visit to Mexico at its president’s invitation was steeped in controversy in both the United States and in Mexico, particularly because he went directly from the Distrito Federal to Phoenix, Arizona, in order to speak about immigration at an event there

“Mexico will pay for the wall, 100 percent. They don’t know it yet, but they’re going to pay for it,” Trump said during his immigration speech in Phoenix, Ariz, Wednesday night. 

Peña told Trump in an unprecedented meeting between the two that Mexico would not be paying for the wall.

“At the start of the conversation with Donald Trump I made it clear that Mexico will not pay for the wall,” he wrote on Twitter. “From there, the conversation addressed other subjects and developed in a respectful manner.”

A few days later, Mexico’s finance minister (who had helped arrange the visit) abruptly stepped down from his post without explanation.