The 61-year-old mother of the Real Madrid football star, Dolores Aveiro, was stopped last month while trying to leave Spain for Portugal with €55,000 inside her carry-on luggage, newspaper El Mundo reported on Monday.
Officers of the Spanish Civil Guard temporarily took Ronaldo's mum, a cook by profession, into custody because the amount exceeded the travel limit of €10,000 for traveling abroad.
Because Aveiro could not account for how she had obtained the €55,000, officials confiscated €45,000, but allowed her to continue on to Portugal with the permitted €10,000 amount.
This remaining money will stay in police custody until Aveiro can present documents to show from where exactly the money came.
Trying to leave Spain with an amount of money that exceeds legal limits is not considered a crime, according to El Mundo, but rather an administrative offence.
Aveiro's money is in the custody of customs officers with the Tax Agency, who will negotiate an economic sanction against her because she infringed regulations designed to prevent money laundering.
Aveiro will have to pay the fine to recover the rest of the funds.
Sources told El Mundo that in Aveiro's case, the infringement was most likely due to her lack of knowledge about the legislation.