In the accident early on July 19, two buses collided head-on at Mulibarhi.
Sirajganj district administration formed a five-member committee to look into the accident.
The panel submitted its findings on Wednesday.
Additional Deputy Commissioner AHM Anwar Pasha, who led the investigation, told bdnews24.com the panel blamed the sleepiness of the driver of Sabir Paribahan bus who took the wrong lane.
The bus was unfit, too, he added.
Pasha said they recommended action against bus owner Abdul Gafur and manager Hasan Ali.
Additional District Magistrate Mohammad Qamrul Hasan was named as the head of the panel first. But Pasha was given the charge as Hasan was on leave.
Driver of Sabir Paribahan bus, Abdus Salam, and the driver of Azad Paribahan bus, Menhaz Pradhan, died on the spot.
Road Transport and Bridges Minister Obaidul Quader recently visited the site and ordered the transport services to keep two drivers in long-haul buses to avoid accidents resulting from driver’s sleepiness.