PROTESTERS have jeered the Spanish king's son-in-law before his questioning by a judge about allegations he and a partner funnelled away millions of euros through fraudulent deals.
The investigation has deeply embarrassed the monarchy in a country hard hit by a financial crisis and sky-high unemployment.
The scandal ranks among the worst public relations mishaps the royal household has experienced in the 37-year reign of King Juan Carlos.
Inaki Urdangarin, who has not been charged with a crime, made his way into a courthouse in Palma de Mallorca on Saturday amid tense street scenes where a contingent of around 170 police kept noisy protesters away from the building.
Urdangarin, married to the 75-year-old king's second daughter, Princess Cristina, has denied any wrongdoing.
Urdangarin, facing his second appearance in court, did not stop to say anything but wished about 100 journalists covering the event a curt "good morning" as he walked in accompanied by his lawyer Mario Pascual Vives.
The Duke of Palma, the title held by Urdangarin, had been called to answer questions about whether he used his high-profile status to secure lucrative deals for a nonprofit foundation he ran and then fraudulently diverted money for personal gain.
But the conservative government of Prime Minister Mariano Rajoy has moved to try and shield the king from potential collateral damage inflicted by the Urdangarin case, emphasising Juan Carlos' value to the nation.
Deputy Prime Minister Soraya Saenz de Santamaria defended the king's role three times during a news conference following Friday's Cabinet meeting, highlighting how the monarch had worked "for stability and democracy" in Spain.
Judge Jose Castro will question Urdangarin about three alleged offences against the Treasury, including corporate tax fraud related to his foundation and matters linked to his personal income tax returns.
As stated in the writ of summons, the judge also intends asking about alleged bank accounts in tax havens such as Andorra, Luxembourg and Switzerland.
Carlos Garcia Revenga, Cristina's personal secretary, was also scheduled to answer questions on Saturday.
A week ago, Urdangarin's former partner, Diego Torres, faced detailed questioning by Castro and it is reported many potentially damaging documents were handed over to the judge.
Urdangarin was summoned by Castro to the same court last February when the duke was quizzed over large contracts he secured from regional governments for his foundation.
He is suspected of then subcontracting the work to private companies he also oversaw, sometimes charging the public purse unrealistically inflated prices and syphoning some of the income to offshore tax havens.