The case, officially a murder investigation now, is still shrouded in mystery and much will depend on the findings of the autopsy. The board has been formed to ensure a proper postmortem.

Dr S Batabyal, head of forensic medicine at the Calcutta Medical College & Hospital, told The Indian Express that the board comprised a professor, assistant professor and a laboratory demonstrator.

Dr Batabyal had also conducted the autopsy on the body of Rizwanur Rehman. The body of Manna, a key witness in the Rizwanur case, was found by the railway tracks Wednesday morning.

The board is expected to finalise the report within the next couple of days and it might be handed over to the authorities by the weekend, said Batabyal.

There are several things to consider including the judicial aspects while preparing the postmortem report. "It will state if the injuries are natural or unnatural, the number of injuries, condition of the body. The viscera will also be analysed," Batabyal said. The autopsy reports prepared by Walsh hospital and the Police Morgue will also be tallied.

The autopsy at the Police Morgue attached to the CMCH had been conducted on Thursday. It was the second autopsy after the family objected to the first conducted at the Serampore Walsh hospital in Hooghly, saying it was done in a "hurried" manner and without a magisterial inquest. The cremation was held at the Shibpur crematorium late on Thursday evening.

The State Criminal Investigation Department (CID) has, meanwhile, taken over the case though the family is demanding a CBI inquiry.

Home Secretary Ardhendu Sen, however, said the government was not considering handing over the case to the CBI at the moment.

"We are waiting for the postmortem report. We have not received the report of either autopsy," Sen said.

On Friday, a CID team led by Special IG and DIG (CID) Nirajnayan Pandey inspected the site where Manna's body was found. Pandey had investigated the Rizwanur case when that case was with the CID.

Aided by sniffer dogs, the team recovered the SIM card and a mobile phone battery, said Assistant Director-General (CID) Bhupinder Singh.

"We will examine the objects. We are yet to receive any autopsy report. We cannot comment on the nature of death," Singh said.

Officers in the department said experts from the state forensic laboratory also visited the spot and collected samples.