The lawyer for a man whose dog allegedly attacked and killed a woman on Wednesday said her client is shocked by what happened.

Audrey Amzallag said her client Franklin Junior Frontal was in school when the attack occurred and had left the dog in his home. He told her he isn’t sure how the dog got out.

The pit bull escaped from Frontal's backyard into Christiane Vadnais', where the attack took place. Police said the dog was so aggressive when they arrived, they had to shoot it to get close to Vadnais, who was declared dead at the scene.

"He left home, as normal to go to school," said Amzallag. "When he came home, that's when he saw that there was an incident with his dog. About what happened, unfortunately even he's not sure what happened."

She said Frontal did not leave a gate open and confirmed police are investigating for potential charges of criminal negligence.

Frontal has owned the dog since it was one-month-old and it was seven-years-old at the time of the attack. Amzallag confirmed the dog had been aggressive on two prior occasions: once when Frontal had tied it to a pole while he entered a depanneur, the animal got loose and latched onto another man’s sleeve and on another occasion in Frontal's home, the dog bit his cousin, who they maintain the animal thought was an intruder.

Her client also told Amzallag that in 2015, when he was having problems in his life, including legal issues, he sought advice online and from the SPCA regarding the dog’s behavioral problems.

"I know he started walking him at a specific time, which is good for that animal," she said. "He also gave him special treats when the dog did something good."

On Friday, flowers had been left at 55-year-old Vadnais' home. A spokesperson for the STM, where she worked, said the tragedy had touched Vadnais' fellow employees profoundly.