Inaki Urdangarin signed himself into the Brieva prison in Avila at around 8:00 am (0600 GMT). He had been given a five-day deadline last Tuesday to appear at a penal institution of his choosing for the five-year 10-month sentence.
The 162-cell mostly-woman’s prison has a small separate area for men and was chosen for its proximity to Madrid to ease visits by his wife, Princess Cristina who is the sister of King Felipe VI, newspaper El Pais reported.
Urdangarin was found guilty in February last year of using royal connections to win public contracts to put on events through his non-profit organization, the Noos Foundation. He then overcharged for the events and hid millions of euros in proceeds abroad.
Princess Cristina, who lives in Geneva with their four children, was acquitted of being an accessory to tax fraud after a year-long trial of 18 defendants in the probe of the charity run by her husband.
