The parents of gunman Seifeddine Rezui, who on 26 June massacred 30 Britons and eight others on the beach of Tunisian holiday resort town Sousse, believe he was brainwashed and "framed" for the attack.
Rezui was filmed walking along the beach in black shorts carrying a gun before he opened fire on sunbathers in Sousse two weeks ago. He can be seen running away from the scene.
But his family believe he is innocent and was put up to the crime.
In an interview with Sky News his mother Radhia Manai said the previous day he had been at home with his brother taking pictures on his computer before he hugged her and told her he was going to stay with a friend for a night.
"From that moment I didn't see him. The next day the police knocked at our door. We didn't have any idea what happened. I thought he was with a friend in Tunis. I didn't believe it. Even now, I swear to God, I don't believe what happened."
Manai says she is convinced he was "just walking" and never gunned down the tourists. "I want to know who fired and then framed him," she said.
She did not mention a group or individual behind the attack.
Father Abdul-Hakim Rezgui said: "I say to the tourists: God bless those who died. And God bless my son. My son was not capable of this. Bad guys tricked him and God will give him what he deserves."
Their interview comes as the Foreign Office told all tourists to leave Tunisia as another terrorist attack was "highly likely".
Foreign Secretary Philip Hammond said: "Since the attack in Sousse the intelligence and threat picture has developed considerably, leading us to the view that a further terrorist attack is highly likely.
"The Tunisian investigation into those behind the Sousse attack and that on the Bardo museum earlier this year is ongoing and the Tunisians have made clear they want to track down further individuals who they suspect may have links to this attack."