Lac-Mgantic rail disaster trial begins in Sherbrooke, Que.

More than four years after a runaway train exploded in flames anddestroyed the centre of the town of Lac-Mgantic, Que., on July 6, 2013,killing 47residents, the first witnesses have testified at the trial of three men charged with criminal negligence.

Images oftrain cars covered in oil, scorched rail ties, and smoke billowing overLac-Mgantic'sdowntown core were among the first pieces of evidence presented to the jury.

The trial began with the three accused solemnly reiterating theirpleas of not guilty in front of Superior Court JusticeGatanDumas, the jury and a courtroom full of reporters.

• Tears, exemptions as jury selection gets underway in Lac-Mgantic rail disaster trial

The three former Montreal, Maine and Atlantic (MMA) Railway employees on trial are:

• ThomasHarding,56, the train engineer and conductor on the night of the disaster.
• JeanDematre, 53, the operations manager for the railway company.
• RichardLabrie, 59, the railway traffic controller.

The three men are each charged criminal negligence causing 47 deaths.

Steven Monteambeault, a former police officer and crime scene investigator on duty the day of the explosion, was the first witness to testify.

Hepresented thefirst piece of evidence, a 13-minute video he took from a helicopter hours after the explosion.Flames were still visible in the main zone.

The next witness was crime scene technician and Sret du Qubec officer Jacques Lafrance, who was tasked with documenting the scene and assisting investigators.

Lafrancedescribed to the court the dozens of photographs he took of the wreckage, explaining photo-documenting the disaster had been part of his job, along with gathering evidence.

Crown outlines its case

As the three accused sat in the Sherbrookecourtroom, taking notes and sipping water, Crown prosecutor Vronique Beauchampoutlined how she and her colleagues will attempt to provethethree men are responsible, either by an act they committedor by certain omissions, for the runaway train and explosion.

Beauchamptold the jury the Crown will prove all three men were aware of a mechanical problem with the train before the derailment, yet each failed to take the necessary precautions to secure it.

She will play audio and video recordings of the three men in the hours leading up to the tragedy, and will present a total of 36 witnesses, she said.

Earlier, Dumas gave lengthy instructions, lasting almost 45 minutes, in both Englishand French to the four women and 10 men sworn in as jurors last week, telling them to remember that MMA is not on trial.

"These people are not accused of acting together to commit criminal negligence,'' he went on, saying the proceedings will operate as three distinct trials for the co-accused.

Dumas also warned the jury of the importance in keeping their conversations confidential, and to not form an opinion before they hear all of the evidence.

Several residents of Lac-Mgantic made the trip to Sherbrooke for the opening of the trial.

Proceedings are scheduled to run until just before Christmas.

Thomas Walsh, the defence lawyer for Harding, said his client would probably take the stand at some point during the trial.

Walshsaid he was happy with the first day of the proceedings and that he believed the prosecutor had been fair in her opening remarks.

"We're very optimistic. Mr. Harding, as you can understand, is very anxious and he has been waiting for this for a very long time, and he's happy it has finally arrived."

3 weeks to screen jury

It took three weeks to screen more than a thousand potential jurors for their ability to speak and understand both English and French, assess their impartiality toward the accusedand grant exemptions.

The jurors who will ultimately decide the fates of the three men were sworn in on Friday.

Walsh said he is very happy with the jury, and that his client is anxious for the proceedings to get underway.

"He's afraid like anyone else would be, but he's happy it's finally going to be over one way or the other," said Walsh.

The maximum sentence for a charge of criminal negligence causing death is life in prison.