As Saudi Crown Prince Mohammed Salman moved to tighten his grip on power over the past few years, detaining senior royals and opponents, one person has eluded him - a former top-ranking intelligence official who was close to a key rival to the throne.

In recent months, the crown prince (photo, above) - known by the initials MbS - has increased pressure on relatives of Saad al-Jabri, including detaining his adult children, to try to force his return to the kingdom from exile in Canada, the former intelligence official’s family say. In the crown prince’s sights are documents Jabri has access to that contain sensitive information, according to four people with knowledge of the situation.