SHERBROOKE, Que. -- The lawyer for one of three men charged with criminal negligence in the deadly Lac-Megantic train derailment tried to distance his client Thursday from the railway at the heart of the 2013 disaster.

In his closing arguments, Gaetan Bourassa told jurors that Jean Demaitre, the manager of train operations that fateful night, had no say in safety-related decisions made in the United States by the parent company of Montreal, Maine and Atlantic Railway.

MMA's reputation in Quebec has been all but irredeemably tarnished since a runaway train owned by the company and carrying crude oil derailed in Lac-Megantic and exploded, killing 47 people and destroying part of the downtown core.

"Do not associate Jean Demaitre with the company," Bourassa told the jury. "There is a mammoth distinction between the two."

Bourassa also appeared to target train conductor Thomas Harding, one of Demaitre's two co-accused, when he said the crack in the chain of security occurred at the first link.

"You must remember that Mr. Demaitre was the third and last link in that security chain," Bourassa said.

Harding had stopped the train on top of a slope in nearby Nantes on the night of July 5 before it began moving on its own in the wee hours of the morning and barrelled into Lac-Megantic.

The Crown argued in its closing arguments Wednesday that Harding applied only half the required level of brakes and didn't test them to ensure they were working properly before he left for the night.

Bourassa also told the jurors they must make a distinction between negligence and criminal negligence.

Demaitre, Harding and traffic controller Richard Labrie each face one count of criminal negligence causing the death of 47 people. They have all pleaded not guilty.

Bourassa tried to undermine the credibility of some of the Crown's witnesses, reminded the jury his client is entitled to the presumption of innocence and added the burden of proof was squarely with the prosecution.

Once Bourassa finishes, Labrie's attorney will present his arguments before Harding's does likewise, probably Friday.

Quebec Superior Court Justice Gaetan Dumas will give his instructions to the jury next week