The three-member committee formed to investigate how the Holey Artisan Cafe attack convict Rakibul Hasan Rigan got the international militant outfit Islamic State's (IS) cap has found out that it was brought from the prison.
Mahbub Alam, joint commissioner of the Detective Branch of Dhaka Metropolitan Police and the head of the probe body, confirmed the matter to The Business Standard.
He said the probe report would be filed soon.
"During primary investigation, we came to know that the cap was carried from the jail. Rigan carried the prayer cap in his pocket," Mahbub added.
The Anti-Terrorism Tribunal on Wednesday convicted seven accused, including Rigan, and sentenced them to death over the gruesome Holey Artisan attack in Dhaka's Gulshan that took place on July 1, 2016.