Most people point to these irregularities and contradictory information furnished by the authorities after the accident early Monday. Sainthia town in Birbhum district is over 190 km from Kolkata.
There is still no clarity on the timing of the accident. As the first reports of the accident trickled in, a railway spokesman put the timing of the collision between the speeding Uttar Banga Express and the stationary Vananchal Express as 2.15 am.
The logbook at the Sainthia station, however, puts it at 1.57 am.
But records at the Gadagharpur station where the Uttar Banga made an unscheduled halt said it was given the clearance to depart at 1.55 am.
Officials said it is not possible for a train like Uttar Banga to cover the 7.14 km distance between Gadadharpur and Sainthia stations in two minutes.
"Actually, the Vananchal Express, running five hours and 32 minutes late, had reached Sainthia station at 1.52 a.m. and was directed to platform number 4. At 1.57 it was asked to resume its journey. The train started but stopped after 300 metres," Santosh Pal, a tea stall owner at Sainthia, said.
Government Railway Police sources said passenger trains frequently overstay for loading and unloading of goods not only in Sainthia but all across India, for which the carriers "grease the palms of all concerned, including railway officials".
"The Vananchal could have stopped because its chain was pulled. Or it may have stopped on its own. But it seems it was to hide the fact that it had stopped soon after starting that the time of the accident at the logbook entry was noted as 1.57 a.m.," said a railway employee.
However, later in the day, Railway Board chairman Vivek Sahai said the time when the Uttar Banga Express hit the Vananchal Express from the rear was 2.01 a.m.
Another theory being floated is that both the driver and assistant driver of the Uttar Banga Express had been drugged and sedated.
A senior police officer said a final conclusion on the 'drugged theory' could be reached only after getting the autopsy and viscera reports. "We are yet to receive the postmortem report. The viscera report, which will lead us to the final conclusion on this aspect, can be available only after a week.
"Now those claiming that the drivers were drugged should back their argument with some evidence. So far there is none. So it is best not to make such allegations at this juncture," he said.
"And even if for arguments' sake we accept that they were indeed drugged, how can you explain that two trains had come on the same downline? Due to the interlocking system, a driver can only control the speed of the train. People concerned outside direct it to a particular platform.
"When the station employees and officials saw that Uttar Banga was also approaching platform 4, why didn't they direct it to some other platform? Or the train could have been redirected to hit the buffer, which is there to protect trains from such accidents. So prima facie, some negligence was there on the part of people whose responsibility was to control the train from outside," he said.
Regarding the charge that the train was speeding in the vicinity of the accident spot, an employee said: "Uttar Banga is a big train, bigger than the platform at Sainthia.
"So its engine and a couple of coaches always stop ahead of the platform. As such expert drivers move at high speed and confidently apply the brake at some point in the platform to stop the train exactly where they want," he said.
Such drivers hardly ever use the speedograph to check the speed of the train, he said.
He said the exact speed of the train and whether it had violated the upper speed limit could be ascertained only after checking the speedograph.