An Ottawa jury has found Marc Leduc guilty of two counts of first-degree murder in the killing Pamela Kosmack in 2008 and Leeanne Lawson in 2011.

Kosmack and Lawson's families clapped and cried in relief and hugged the Crown attorneys and police as the verdicts were read in the packed Ontario Superior Court room Thursday.

Justice Hugh McLean thanked the 12-person jury for its diligence in what he described as "a long and difficult exercise."

Leduc, 59, will serve two concurrent life sentences with no chance of parole for 25 years. The sentence also carries a lifetime weapons ban and Leduc will be registered on a sex offender database.

When McLean asked Leduc if he had anything to say, he replied in a hushed tone, "No." Leduc had pleaded not guilty to two counts of first-degree murder when the trial began in late April.

"I would express the absolute disgust I feel for the unmitigated horror you inflicted on these vulnerable people," McLean said to Leduc.

'I'm sorry I wasn't there to prevent this'

Pamela Kosmack's brother Jeff, sister Cindy Murch, brother-in-law Darrin Murch and Murch's mother Joan Murch said they waited eight years for "justice." (Judy Trinh/CBC) Family member of both victims gave emotional victim impact statements after the verdict was read.

The court heard from Pamela Kosmack's daughter Anona Kosmack, who said her mother was "graceful, strong and dignified despite the brutality she faced alone."

"In a cold loveless place, an invisible monster had snuffed out the intricate and powerful beacon of light that was my mother," she said. She described how she has trouble trusting people, especially men, and says she has depression and suffers from PTSD.

She concluded by saying "She lives on in me and I choose to serve her memory with humility and strength"

Kosmack's brother Jeff Kosmack broke down as he told the court how much he missed his sister with the "beautiful, warm heart."

"I'm sorry I wasn't there to prevent this," he said.

'I've never experienced such traumatic pain'

Leeanne Lawson's mother Cindy Lawson said she didn't come to court to lash out or seek revenge.

"It's because of Jesus I forgive you," she said to Leduc.

"I have never experienced such traumatic pain," she continued. "My little boy should not know the pain of losing his half-sister. I miss Leeanne's face, her voice, going to the movies and walking with her."

Melissa Sauder said her sister Leeanne Lawson was a young woman with dreams of becoming a veterinarian.

Pamela Kosmack, left, was found beaten to death near a bike path close to Britannia Park in June 2008. Leeanne Lawson, right, was found dead in a parking lot in Ottawa's Lowertown neighbourhood in September 2011. (CBC) "No amount of counselling can help us make sense of this," she said, but added that her sister's memory lives on in her.

DNA found on both women

Kosmack and Lawson both struggled with addiction and sometimes worked in the sex trade, and both had known Leduc, the court heard. He and Kosmack frequented the same Britannia pub, and Lawson and Leduc were both living at the Shepherds of Good Hope in 2011.

The badly beaten body of Kosmack, 39, was found naked from the waist down on June 4, 2008, on a bike path close to Britannia Park.

The body of Lawson, 23, was found more than three years later, on Sept. 2, 2011, also naked from the waist down, lying face down between a fence and a Hydro Ottawa substation on King Edward Avenue.

Foreign objects had been left in both women, they had both been dragged short distances from where the struggles appeared to have taken place, both were beaten mainly about the head, and autopsies concluded they both died of neck compression that showed signs of manual strangulation.

The Crown's case against Leduc hinged mainly on DNA evidence gathered from the bodies of both women and at both crime scenes.

The chances of another man matching that DNA profile range from one in 98 trillion to one in 890 quadrillion, depending on the sample, court heard during the trial.

Marc Leduc, 59, had pleaded not guilty to first-degree murder in the 2008 and 2011 deaths of Pamela Kosmack and Leeanne Lawson. (Laurie Foster-MacLeod) The defence, led by Ian Carter, argued that there are no eyewitnesses in either of the homicides and said police did not do enough testing of the evidence to make it anything more than circumstantial.

Carter argued that because police did not conduct enough swabs, there was the possibility they missed another person's DNA on either of the two women's bodies.

Leduc convicted in 2012 sexual assault

Police had obtained Leduc's DNA after he was arrested and charged in the aggravated assault of a 19-year-old woman in a November 2012 attack.

Leduc pleaded guilty to breaking into the woman's apartment and sexually assaulting her while brandishing a knife.

Leduc was in custody for the 2012 attack when he was charged with first-degree murder in the deaths of Kosmack and Lawson. The jury did not hear the details of the sexual assault in court.