Madrid (CNN) -- The son-in-law of Spain's King Juan Carlos arrived in court to testify before a magistrate Saturday as a suspect in a fraud scandal that has created unprecedented problems for the popular royal family.
Inaki Urdangarin, who was granted the title of Duke of Palma when he married the king's youngest daughter, Princess Cristina, in 1997, is under investigation for allegedly diverting public funds that were earmarked for his foundation for private use.
Urdangarin walked into the courthouse in Palma de Mallorca past throngs of reporters and news cameras, even though the court authorized him late Friday to avoid that scene on an "exceptional basis and strictly for security reasons" and to drive right up to the building. All the other suspects in the case who previously testified had to walk in, past the media.
Urdangarin, with a serious look on his face and flanked by his lawyer, stopped briefly to make a statement to a group of reporters who were allowed inside a court-designated security zone.
"I am here today to demonstrate my innocence," Urdangarin said. "During these years I have carried out my responsibilities and have made decisions in a correct manner and with total transparency. My intention today is to clear up the truth about the facts."
As Urdangarin walked in, jeers and chants from anti-monarchy demonstrations, on nearby streets outside of the security zone, could be heard.
No trial has been set in the case, which has riveted national attention.
"People can understand if politicians, businesses or unions do this, but when it happens in the royal family, that is a hard blow for all Spaniards," said Gerardo Correas, an expert on royal affairs who runs the International School of Protocol in Madrid.
The investigation, officially secret, has been top news for months in Spain as details were reported. The court in Palma de Mallorca has publicly confirmed only the basic charge of misappropriation of public funds and named Urdangarin and some former associates as suspects.
Urdangarin, an Olympic medalist in handball, led a private foundation that secured lucrative contracts from regional governments to promote sports and tourism.
As the case gained notoriety, the royal palace announced last December that the Duke of Palma would not take part in official ceremonies, which is a key role for members of the royal family.
The royal household is widely respected for the king's role, as head of state, in guiding Spain to democracy after the dictatorship of Francisco Franco.
Also last December, the royal family publicly revealed its finances for the first time in an effort to boost public confidence and transparency.
Then the king, in his annual Christmas address, issued a warning to public officials:
"Fortunately, we live in a state of law, and any objectionable action should be tried and punished according to the law," the king said. "Justice is for all."
Correas said the king "was clearly referring to the Duke of Palma, distancing himself from the duke."
Madrid's wax museum already has moved the image of Urdangarin away from the royal family. He now stands alone in the section for sports figures.
Urdangarin will mount a vigorous defense, his lawyer, Mario Pascual Vives, told reporters earlier in Barcelona.
"I am still convinced that he is innocent," Pascual Vives said. "And I have always said that her highness, Princess Cristina, is not involved in this at all."
Urdangarin and the princess have lived with their children in Washington, D.C., in recent years.
The testimony took place in a closed-door session, with no cameras allowed. In attendance were prosecutors, Urdangarin's defense lawyer and lawyers representing other suspects in the investigation. The attorneys for the other suspects -- in addition to the investigating magistrate -- will have a chance to question Urdangarin, according to state-run television TVE.
The judge has not said publicly when the investigation might conclude. After that, the judge may set a trial, and indict suspects who currently face only preliminary charges, or clear these suspects of all charges.