Citing a lack of evidence, the Crown prosecutor's office has decided not to charge the owner of the dog that killed Christiane Vadnais.
The 55-year-old woman was mauled to death in her backyard earlier this year when her neighbour's animal made it through a fence.
This was the third known attack by Lucifer, a dog that was registered as a boxer, but which owner Franklin Junior Frontal said was a pit bull.
Police killed the dog at the scene.
In an interview with CTV Montreal, Vadnais's sister said she learned about the decision two weeks ago.
"When we learned there would be no criminal charges, we were extremely disappointed," Lise Vadnais said.
"We talked about it for a long time with the prosecutor and investigator, to try and understand why it couldn't go further."
Vadnais said it was "frustrating" to learn that the evidence that was collected would not be enough to secure a conviction.
Part of the problem was that although the dog had attacked people and animals on two other occasions, no official complaints had ever been filed.
Montreal lawyer Jeff Boro said prosecutors would have had to be able to prove Frontal knew an attack was likely in order to get a conviction.
"The prosecutor, in a general sense, has to have evidence that the owner of the dog acted in an irresponsible way, was negligent," he said. "The term used in the criminal code is reckless disregard for the safety of others."
Vadnais said Frontal maintains his dog was locked inside, and he does not know how it got out.
Frontal's lawyer, Audrey Amzallag, said her client regrets the incident.
"Obviously it is a very hurtful situation for the family and nothing in this case will bring back the victim, but the criminal code and the prosecutors did what they had to do and it is closing this chapter," said Amzallag.
Vadnais she remains convinced that pit bulls are a uniquely dangerous type of dog.
"I don't want it to become trivialized, that we put them all in the same boat," she said. "For me, it's clear, with pit bulls, it's all-out attacks. It's not just bites, it's traumatic attacks. We can't have that in our society."
Her family wants to see more governments restrict vicious dogs, and Montreal Mayor Denis Coderre agrees.
The attack kicked off a debate on pit bull-type dogs in Quebec, culminating in bans in several cities, including Montreal.
"Some people will be sad because we're thinking of Madame Vadnais who died, but frankly it just make me stronger to have the regulation that I'm putting forward," said Coderre.
Montreal's ban on pit bulls is currently the subject of an injunction pending a legal challenge by the SPCA,. The city of Montreal has appealed the injunction.
In the meantime Vadnais's family said it will launch a civil suit against Frontal.
