Rafik Chelli told The Associated Press today that Seifeddine Rezgui, a Master's student in electrical engineering at Kairouan University, sneaked into Libya in January and trained near the western town of Sabratha.
The two attackers that carried out the Bardo museum attack in Tunis in March that killed 22 people were there at the same time.
The attack near the resort town of Sousse was the worst in Tunisia's history and has devastated the country's vital tourism sector.