Raihan, who was beaten to death in police custody at the Bandar Bazar police outpost, had 111 injury marks and two of his nails were pulled off, according to the autopsy report.
His stomach was empty and there was only acidity liquid. He had severe internal bleeding because of excessive physical torture.
He was tortured between two and four hours before his death. About two litres of blood was found underneath his skin, said Dr Mohammad Shamsul Islam, head of the Forensic Department.
The autopsy report was handed over to the Police Bureau of Investigation (PBI) on Saturday night.
Surveillance cameras at Bandarbazar Police outpost show Raihan being brought in around 3:09am on October 10 in normal condition. He was seen being taken to Osmani Medical College Hospital at 6:24am and he died around 7:50am.
Later, the hospital authorities conducted an autopsy and found that Raihan died due to physical torture.
"His organs were damaged due to hypovolemic shock and neurogenic shock," said Dr Shamsul adding, "the actual reason will be known after getting a viscera report."
Raihan, 34, a resident of Akharia in Sylhet city, was beaten to death in police custody at the Bandar Bazar police outpost on October 11, his family said.
His body was exhumed for a second post-mortem examination and buried again on October 15.
The district administration allowed the exhumation following an appeal by Kotwali police Sub-Inspector (SI) Abdul Baten, the investigation officer of the case.
PBI is currently investigating the case at the instructions of the police headquarters. The Sylhet Metropolitan Police has handed over the documents of the case to PBI.
The authorities on October 12 suspended four policemen, including the in-charge of Bandarbazar Police outpost Sub-Inspector Akbar Hossain, in connection with the death.
PBI said it is looking for suspended SI Akbar and has written to the immigration police to prevent him from leaving the country.
Raihan's wife Tahmina Akter Tanni filed a case at Kotwali Police Station on October 12 accusing a number of unidentified people.
Meanwhile, the lawyers in Sylhet vowed to refrain from providing legal assistance to those involved in Raihan killing.
Sylhet District Lawyers Association took the decision at a view-exchange meeting on Saturday.