MADRID (AP) — Inaki Urdangarin, the husband of Spain's Princess Cristina, has begun testifying in the tax and embezzlement trial the couple and 16 others are facing.

The case centers on accusations Urdangarin used his former title of Duke of Palma to embezzle about 6 million euros ($6.6 million) in public contracts for sporting events through a non-profit institute he co-ran.

Among the companies that allegedly benefited was Aizoon, a property consultancy firm he owned with Cristina, the sister of King Felipe VI.

Urdangarin began testifying Friday and faces a possible sentence of 20 years.

Cristina is charged with two counts of tax fraud and faces a possible eight-year sentence. She is expected to testify next week and is the first Spanish royal to face criminal charges since the monarchy's restoration in 1975.