The decision to allow the Western Sahara leader into Spain in April angered Morocco.
Spain's former foreign minister has defended the decision to receive the leader of the Polisario Front for COVID-19 treatment.
Arancha González Laya is under investigation for admitting the Western Sahara leader, Brahim Gali, into Spain in April.
The former minister told reporters on Monday that Gali's entry into Spain was "in accordance with the law".
González Laya had earlier testified in person before a judge in Zaragoza over the matter, which has caused a diplomatic crisis with Morocco.
"The entry was done, from my point of view, in accordance with the law," she said, "I hope that the judge will soon come to the same conclusion."
Gali arrived in Spain at an airbase in Zaragoza on April 16, travelling on a medical plane from Algeria. He was then admitted in a critical condition to a hospital in Logroño for coronavirus treatment.
The pro-independence Sahrawi leader is a sworn enemy of Rabat, which claims sovereignty over Western Sahara, a former Spanish colony.
His entry into Spain angered Morocco, and more than 10,000 migrants soon entered the Spanish enclave of Ceuta, following a relaxation of controls by Moroccan authorities.
González Laya was summoned for questioning after her chief of staff -- also under investigation -- admitted that she had received instructions from the former minister to facilitate Gali's entry with "maximum discretion".
The judge in Zaragoza had heard that public disclosure of Gali's entry into Spain could "harm" Spain's international relations.
The investigation is examining whether Spanish authorities allowed Gali to enter the Schengen area without documentation or border controls.
Morocco has claimed that Gali "fraudulently" entered Spain with a "usurped identity," but Spain has dismissed the accusations.
The judge in Zaragoza will look for any evidence on alleged crimes of forgery, prevarication and concealment by senior officials of the Ministry of Foreign Affairs.
González Laya has since left her role in the Spanish cabinet after a reshuffle in July.
Meanwhile, Spain's National Court also refused on Monday to prosecute Gali for genocide due to legal formalities.