According to investigation, a police team, led by Ashek, detained Raihan and brought him to the police outpost on 10 October.
On 11 October, Raihan, 34, a resident of Akhalia in Sylhet city, was beaten to death in police custody, said the victim's family.
His wife Tahmina Akter Tanni filed a case at Kotwali police station the following day accusing a number of unidentified people.
Besides, the authorities on 12 October suspended four policemen, including the then in-charge of Bandarbazar police outpost Akbar, in connection with the death.
Three policemen including Ashek were withdrawn on the same day.
The case was transferred to the PBI.
Besides, the SMP formed an investigation committee, headed by its additional deputy commissioner Shahrier Al Mamun, to look into the death of Raihan. After a primary investigation, they found some policemen guilty over the incident.
After the autopsy, physicians said they found 111 injury marks on Raihan's body and two of his nails were pulled out.
On 22 October, former SMP commissioner Golam Kibria was transferred over widespread criticism of the role of police after the death of Raihan.