A six-man, six-woman jury found Curtis Bonnell guilty after deliberating for about six and a half hours late Friday and early Saturday.
Family members of the victim — Hilary Bonnell — wept openly in court as the verdict was read. Curtis Bonnell showed no emotion and members of his immediate family quickly left the courthouse.
Outside the courthouse, Hilary's mother, Pam Fillier, sobbed as relatives and friends hugged her.
She said it will take a long time to heal.
"I don't think I will ever really have true closure," said Fillier. "She was my only little girl and him being guilty doesn't give her back to me."
The conviction carries an automatic sentence of life in prison with no chance of parole for 25 years, however, Judge Fred Ferguson has scheduled a sentencing hearing for Nov. 14 to allow members of Hilary's family to read victim impact statements.
During the seven-week trial at the Court of Queen's Bench in Miramichi, the Crown alleged the 32-year-old Bonnell picked up the girl while driving on a rural stretch of road, sexually assaulted her and killed her.
Prosecutor Bill Richards told the court that Bonnell buried her body near an old firing range to avoid detection.
The girl's disappearance from the Esgenoopetitj First Nation on Sept. 5, 2009, sparked an extensive search and gripped the native community for two months.
Bonnell was arrested on Nov. 8, 2009, and led police to the burial site the next day.
During subsequent interviews with police that were entered as evidence, Bonnell told officers that he fought with Hilary, sexually assaulted her and killed her.
But during the trial, Bonnell offered a different version of events.
He testified that he woke up on Sept. 5, 2009, after a night of alcohol and drugs to find Hilary dead next to him in his pickup truck. He said he didn't know how she died, but panicked and buried her.
Bonnell said police filled his head with what they believed happened, and he just told them what he thought they wanted to hear.
The court was told that autopsy and toxicology reports were inconclusive on the exact cause of death, but termed the manner of death as a homicide.
A forensic pathologist called by the defence disagreed with the homicide determination.
Dr. David Chiasson of the Hospital for Sick Children in Toronto said at best it was "criminally suspicious." He suggested Hilary could have died as a result of "positional asphyxia," which can happen when someone is intoxicated and they get in a slumped position that constricts their airway.
Following the trial, Richards told reporters that the lack of a clear cause of death made the prosecution difficult.
"We had to give the answer to the jury circumstantially with the clothing on Hilary as she was found, the laceration above her eye as well as that very, very important and crucial text message," he said. "Those are the things I think sealed the first-degree murder conviction in the jury's mind."
During the trial, the jury was shown two text messages that Hilary sent to Haylie Bonnell, the accused's sister, on the morning she disappeared.
They read, "Please answer me I'm scared," and "OMF text me I'm scared."
Haylie's phone battery had died and the messages weren't retrieved until five days later.
RCMP Sgt. Greg Lupson said police had little to go on after the girl's sudden disappearance.
"It is just good old fashioned police work that led to this," said Lupson on Saturday. "There was no one piece of critical evidence that was pointed to."
Defence attorney Gilles Lemieux said he was surprised Bonnell was found guilty of first-degree murder.
The jury had the options of first- or second-degree murder, manslaughter, or not guilty.
He said an appeal is being considered.
"We are definitely going to look at our different avenues as far as that goes," Lemieux said as he left the courthouse. "I fully anticipate that we'll get instructions to file an appeal."
The defence would have 30 days to file a notice of appeal, following the Nov. 14 sentencing hearing.