"I hope I'm not going to get shot."

That's a quote from the CEO of the rail company responsible for the train that doused Lac-Megantic with flaming crude oil, according to Canadian broadcaster CBC.

Edward Burkhardt plans to travel Wednesday to the Quebec town laid to waste over the weekend when 72 tanker cars jumped the track and unleashed an inferno.

It killed at least 15 people, and 35 are still missing, feared dead, likely vaporized by the intense blaze, officials have said.

Burkhardt has been receiving hate mail.

It didn't help when he told reporters where part of the responsibility lies.

"I think the fire department played a role in this," he said Tuesday. "That's incontrovertible."

Burkhardt does not blame firefighters, he said, but he believes that what they thought was due diligence may have actually helped turn the parked locomotive train into a runaway oil bomb.

The fire department in Nantes has rejected the notion.

Crime and blame

Investigators have asked fire crews to stop spraying down the still-smoldering wreckage to preserve as much of the remaining evidence as possible.

Some of it has led them to believe that a "criminal act" may have contributed to the train crash, provincial police Capt. Michel Forget said Tuesday.

The investigation into the cause of the disaster has shifted its focus to possible foul play.

"We are no longer treating this as just an accident," Quebec police spokesman Benoit Richard said Wednesday.

The gutted center of town and the crumpled hulls of the tanker cars are now a crime scene.

Burkhardt wants to look over investigators' shoulders there.

Where there's smoke

Nine black tanker cars filled with crude oil still stand silently in the town of Nantes.

They remained behind when the rest of the train they were attached to broke away and began rolling late Saturday down an incline, seven miles uphill from Lac-Megantic.

A short time earlier, a fire broke out on the train, and firefighters came to extinguish it. They alerted the railroad trackman, Burkhardt said.

That man, whose job it is to attend to the integrity of the rails, went down to have a look and phoned Montreal Maine and Atlantic Railway (MMA) to tell the company what he saw, Burkhardt said.

"The train was still there," Burkhardt stated.

One firefighter remained behind. The fire crew had "shut down" the train, the rail chief said.

Burkhardt thinks that was a mistake, because it may have included the engine that controlled the brakes.

But by the time MMA found out about the shutdown, it was too late, Burkhardt said. The train was gone.

"I'm of the opinion that the train rolled away rather quickly after being shut down," he said. It must have been right after the trackman left the site. He said he hopes the investigation will shed light on that.

Firefighters not train experts

Burkhardt does not think the firefighters are at fault. They are not experts on trains, he said. He wishes they'd have involved the train's engineer, who was sleeping at a nearby hotel.

"It's easy to say what should have happened," Burkhardt lamented.

Besides, the firefighters' shutting down of the the engine's brakes should not have been enough to cut the train loose.

The locomotives and cars also have handbrakes. That should have been enough to hold the train, he said.

"Either a sufficient number were not set on the train," Burkhardt said, or the standard procedure for the number of brakes set was not enough for a train that heavy.

His engineer reported having deployed the hand brakes on a number of tanker cars and on the engines. The brakes on the locomotives eventually held, he said.

They stopped a quarter of a mile away from their original parking spot in Nantes, he said. They did not make it to Lac-Megantic.

He could not explain what happened with the brakes on the 72 oil cars that did.

March of death

What remained of the train picked up speed, because the track between Nantes and Lac-Megantic lies on a 1.2% downward slope, which is relatively steep, a Canadian rail safety official said.

The train rolled into town much faster than a train under an engineer's control would.

"Usually they're traveling between 5 and 10 miles an hour," said Richard. "On that night, this train was going at least between 30 and 40 miles an hour."

Rail traffic controllers can spot runaway trains on major rail lines, said rail safety manager Ed Belkaloul. But the line between Nantes and Lac-Megantic is not one of them.

The town's residents were the first to find out about it.

One who lives near the track said she had never heard a train rumble through town that loudly. It shook her entire house.

Then came the fireball.

CNN's Holly Yan, Umaro Djau, Jonathan Mann, Pierre Meilhan, Joe Sterling and Deanna Hackney contributed to this report.