Police said the selfie made Antoine a suspect in the crime, allowing them to focus their investigation on her, Canadian media reported. Haven't heard from you. "Expectation you influenced it to home safe" - was a preoccupation.
It seemed like the death of the girl was an unsolvable case, but then police made a decision to dig up some information on Facebook and that is when they saw the murder weapon in a photograph. "I miss her so much".
Though the prosecution crafted a strategy of damning information about Antoine from publicly available Facebook posts, mining data through personal devices and social media are on the frontier of criminal justice.
According to CBC reporter Charles Hamilton, who live-tweeted the final submissions in the case from the courtroom, Ms Gargol was found in March 2015, unresponsive, lying shoeless on her back on the side of the road.
However, police were suspicious of the story and used Facebook in an attempt to establish the pair's movements on the night of Brittney's death. Antoine had attempted to cover her tracks by writing, "Where are you?"
Saskatoon's Senior Crown Prosecutor Robin Ritter told CNN the wide webbed black belt Antoine was wearing in the photograph matched some marks left on Gargol's vehicle. She hit Gargol and ended up strangling her.
The woman was sentenced to seven years in prison.
The two women readied for a night on the town and snapped the photo before going out, prosecutor Robin Ritter told The Washington Post. She claims that she doesn't actually remember the murder, but knows that she did it. The judge showed some leniency, pointing to Antoine's life of abuse in the foster care system and her apparent remorse.
Her criminal record began with vehicle theft at age 12, two years before she reconnected with her mother, the station reported.
She also falsely told the police that she was with Gargol the night of Gargol's death but had left early to see her uncle.
At that point, she began moving between relatives, group homes and other institutions.
Those issues continued even after Antoine killed her friend.
And the key piece of evidence was a Facebook photo of the pair.
Antoine was arrested in March 2017 and charged with second degree murder and causing an indignity to a body. She threatened the officer with a needle that she claimed was contaminated with the HIV virus. She also tried to make investigators believe that Brittney had left the bar with a stranger the night of the murder.
In court Monday, the victim's aunt gave an emotional impact statement, reports the Toronto Sun.
Members of Gargol's family, have been less forgiving.
"Where are you?" she wrote. "She trusted you", Gargol's stepmother, Kristi Wickenhauser, told the defendant. "And instead you chose to wrap a belt around her throat and squeeze until you ended her life". "That should not have happened", the statement read.
"I will never excuse myself".
She said they got drunk and got into a heated argument which infuriated Antoine and forced her to make such a grave mistake. I am very, very sorry... "It shouldn't have ever happened".