Pique summoned in probe over Spanish Super Cup move to Saudi
The probe has further sullied the image of Spanish football and ensnared disgraced former federation chief Luis Rubiales who was in charge when the decision was made.
A Madrid court placed Pique under investigation in May last year over the contracts to take the Super Cup to the oil-rich Gulf country from 2020.
The deals are worth 40 million euros ($41.2 million) a year and were brokered by Kosmos, a company owned by Pique, while the former defender was still playing for Barcelona.
The court said there were "possible illegalities with criminal implications", including a clause to "guarantee the payment of a commission of four million euros per year to Kosmos".
A document dated Thursday from a court in Majadahonda outside Madrid said "the declaration of Mr Gerard Pique as an investigated party is agreed on March 14".
Rubiales, who faces possible jail time for his forced kiss on star forward Jenni Hermoso in 2023, has always defended the legality of the deal to take the Super Cup to Saudi Arabia.
Pique has also insisted that everything was "legal", saying he was "proud" of the deal.