The railway officials have started the probe into Friday's ghastly fire accident on the Secunderabad-Kakinada Gautami Express, in which 31 passengers were burnt alive.

The inquiry began on Sunday amid speculation over the exact cause of the fire as traces of inflammable grease was found in the gutted S-10 coach from where the fire had started in the wee hours of Friday.

The police and the railway officials have been saying from the beginning that an electric short circuit was the cause of sparking the fire. But what has surprised them is the speed at which the fire spread and destroyed five coaches. The forensic experts during the examination of the burnt coaches found traces of grease near the toilets of the S-10 coach from where the fire had started.

It has left the officials and experts to believe that one or more passengers were travelling with inflammable material in the coach and it contributed to the spread of the fire. However, they were not ready to comment on record pointing out that the Chief Commissioner Railway Safety R P Agarwal was conducting the inquiry.

On the first day of the in camera probe at the Warangal railway station, R P Agarwal recorded the statements of managers and pointsmen of all the stations between Warangal and the point of accident near Ksamudram station. The station masters and other crew members of Chintalapally, Elguru Rangampeta, Nekkonta and Intikanne stations were also summoned to give their version.

The commissioner of inquiry has also appealed to the passengers and other people to come forward and give their statements if they have any information regarding the accident.

The burnt bogies have already been brought to the Kazipet station and experts were closely examining all of them. A burnt stove was also found on S-9 compartment, adjoining the S-10 coach.

While the speculations are continuing about the cause of the fire, the process of identifying the charred bodies was moving slowly. On Saturday 18 of the 31 bodies were identified with the help of forensic and DNA experts. But the process of postmortem on the remaining bodies was stopped on Sunday because of the holiday.

While 27 of the victims were accounted for, there were four additional bodies with out any information about them as they were not mentioned on the reservation chart of the compartments. It is believed that they could be among the passengers who were given spot reservation by the ticket checking staff.

It is believed that one navy sailor G Madhusudhan Rao and another couple Roshni Mukherji and her husband Harishankar could be among them as they are reported missing after boarding the Gautami Express.

With most of the bodies reduced to charred bones and ashes, even the DNA fingerprinting experts were finding it difficult to identify the bodies.