Denis Soulard, a provincial police investigator deployed to Lac-Mégantic on July 6, 2013, after the fatal train wreck, says Thomas Harding, the conductor of the runaway train on the day it derailed and exploded, was helpful to police in the hours after the tragedy.

Harding, 56, is one of three co-accused in connection with the rail disaster, along with Richard Labrie, 59, and Jean Demaitre, 53.  The former Montreal Maine and Atlantic (MMA) Railway employees are all charged with 47 counts of criminal negligence causing death — one for each of the victims of the tragedy.

Soulard took the stand at the Sherbrooke courthouse on Wednesday, the third day of the trial.  

He told the court it was his job to find Harding on the morning of the explosions, but he got a call from his supervisor telling him Harding had gone to the police station and was waiting to meet him.

Soulard told the jury he didn't know anything about trains or railways, but he wanted to know about the brakes, the engine and the fire on one of the locomotives for the purpose of his investigation.  

Soulard said Harding accompanied him and another investigator to the locomotive he'd been driving the previous day and told them everything they wanted to know.

Every question answered
SQ investigator Denis Soulard

SQ investigator Denis Soulard told jurors at the Lac-Mégantic trial that former MMA engineer Thomas Harding was waiting for him at the police station to offer his assistance the morning after the fatal derailment and explosions. (Daniel Mailloux/Radio-Canada)

"He collaborated 100 per cent," Soulard said. "He answered every question we could have about trains."

Soulard said he also remembered Harding pointing out some important documents in the locomotive.

Under cross-examination by defence lawyer Gaétan Bourassa, Soulard told the jury he'd met Bourassa's client, Jean Demaitre — the former operations manager for MMA — in the parking lot of the police station in Lac-Mégantic on the same day.

Soulard said Demaitre contacted his supervisor and granted police access to MMA's audio recordings and emails at the company's Farnham office.

'The system was working 100% perfect'

A former MMA signals and communications technician, Waldimar Huamani-Alfaro, also testified before Superior Court Justice Gaétan Dumas and the 14-member jury, describing how he'd been called to the company's office in Farnham to open the door to investigators who were carrying out a search and seizure operation.

Huamani-Alfaro told the court his job was to make sure the signal was fed from a server in the U.S. to a radio device in Farnham and to make certain that signal was never cut off.  

He said the signal allowed the train conductor to communicate with the railway controller, supervisors and other employees who sometimes have access to the system from their motor vehicles.  Huamani-Alfaro said he had to make sure the line was secure.  

Huamani-Alfaro said he was also responsible for a system called a hot box detector, which detected heat signals on the train and sent a message by radio signal if it discovered a problem.

"This system was working 100 per cent perfect," he said.

Huamani-Alfaro told the court another MMA employee was responsible for the recordings and entering in the correct phone numbers.

The Crown then focused attention on the details of the search and seizure operation at the Farnham office on July 25, nearly three weeks after the deadly disaster.

Jean-François Matton and Mathieu Bouchard, two SQ investigators who carried out that search, described accessing and seizing dozens of emails, audio records and documents.

Bouchard is to be back on the stand Thursday, to face cross-examination.