The mother of Nicholas Thorne-Belance, the five-year-old boy killed in a car crash involving a Quebec provincial police officer driving an unmarked car, said the months since her son died have been excruciating.

Nicholas Thorne-Belance, 5, was fatally injured after an unmarked police car slammed into his father's car. (CBC)

"It’s been a very hard time. We’re not doing that well, but we’re trying to really take it one day at a time right now. It’s a very emotional process," said Stephanie Thorne, in an exclusive interview with CBC/Radio-Canada.

In February, a Sûreté du Québec car travelling at 122 kilometres an hour in a 50-kilometre zone slammed into the side of a sedan turning left on a green light in Longueuil on Montreal’s South Shore.

The sedan was carrying Mike Belance, his 10-year-old stepdaughter and Nicholas.

The boy died in hospital five days after the crash with the provincial police vehicle.

SQ officer not charged

Thorne waited more than nine months to learn the results of the Montreal police’s investigation into what happened.

I want somebody to take responsibility. I want them to stop pointing their fingers at my husband. He didn’t do anything wrong. - Stephanie Thorne

"On Nov. 13, which was nine months after the actual accident, the Montreal police came to my house. It was two officers that came, and they came to announce to me that there wouldn’t be any charges brought forward," Thorne said.

It turned out that the SQ officer behind the wheel of the speeding car was tailing an ex-Liberal under investigation by the province’s anti-corruption police unit.

Four unmarked provincial police cars were involved in the surveillance of Robert Parent, the former director of the Quebec Liberal Party.

The director of criminal and penal prosecutions on Nov. 19 said no charges would be laid against the SQ officer.

"So that same afternoon before the press conference I did meet with them. They went over with me the whole process so that I would understand more how they came to that decision," Thorne said.

She said they looked at a number of factors, but that they seemed to hinge their decision on the fact that Belance had been turning on a solid green light — not a priority flashing green one.

"The emphasis in that press conference seemed to be, ‘OK, there were all those factors, but don’t forget the husband did do this,'" Thorne said.

"My husband had no chance in knowing that speed would be at 122."

SQ officer driving at 122 km/h

Thorne said she didn’t know the specifics of the crash until this month, when she was informed of the SQ car’s speed.

This sedan was carrying Mike Belance and his two children. His five-year-old son suffered a head trauma in the collision and died in hospital. (CBC)

"I knew it was fast, but I couldn’t ever imagine at 122," Thorne said.

She said she was told the SQ officer tried to brake, but that the speed on impact was about 100 kilometres an hour.

"I could just picture my little boy in the back of the car…" she said, trailing off.

On Nov. 24, Quebec Justice Minister Stéphanie Vallée said she was reopening the investigation, this time placing a panel of independent prosecutors in charge of taking a second look into Thorne-Belance’s death.

Thorne wants to believe the system can deliver justice for her son’s death.

"I want somebody to take responsibility. I want them to stop pointing their fingers at my husband. He didn’t do anything wrong. He turned on a green light, could never have known what was coming in front of him … I just want somebody to take responsibility," Thorne said.