Two people charged with first-degree murder in the 2014 deaths of Amanda Trottier and Travis Votour pleaded guilty to lesser charges in a Gatineau, Que., courtroom Tuesday, where chilling new details about their crimes were revealed for the first time.

Trottier and Votour were found dead on the main floor of Votour's home in Aylmer in January 2014. Trottier's then three-year-old daughter was discovered alive upstairs.

Gatineau police charged three people with first-degree murder: Sonia Vilon, René Samson-Vonrichter and Ronald Junior Brazeau.

Brazeau pleaded guilty to the lesser offence of manslaughter last week.

Police allege Brazeau is the head of a drug trafficking group operating in Gatineau, and that he ordered the killings after a drug theft. Investigators alleged Vilon and Samson-Vonrichter carried out the fatal shootings.

Killers get 12 years, life

In court on Tuesday, Vilon pleaded guilty to two counts of manslaughter for both deaths. She also pleaded guilty to several drug-related charges, including cannabis and methamphetamine trafficking.

She was sentenced to 12 years in prison for both killings, with credit for the 38 months she has already served in jail.

Samson-Vonrichter pleaded guilty to manslaughter in Trottier's death and second-degree murder in Votour's death. He also pleaded guilty to five drug-related charges stemming from April 2015, including possession of cocaine, possession of methamphetamine and possession of marijuana.

For the second-degree murder of Votour, Samson-Vonrichter was sentenced to life in prison without the chance of parole for at least 15 years. He was also sentenced to nearly nine years in prison for manslaughter in Trottier's death, to be served concurrently.

He has been banned from possessing weapons for life, and must submit a DNA sample to be entered into a national databank.

Both victims shot in head

According to an agreed statement of facts revealed for the first time Tuesday, ​Samson-Vonrichter and Vilon, both regular drug users, had consumed a large quantity of crack cocaine before arriving at Votour's home on Jan. 6, 2014 to settle a grudge.

The situation quickly deteriorated and a .22-caliber that Vilon was holding accidentally discharged, striking and killing Trottier. A panicked Samson-Vonrichter grabbed the weapon from Vilon and fired several rounds at Votour, striking him. He then fired the rifle again at Trottier, who was likely already dead.

An autopsy revealed Trottier had been shot in the head twice, while Votour had been struck once in the head and once in the torso.

The police investigation revealed no sign of a break-in, but eventually zeroed in on Brazeau. Undercover agents then targeted Vilon, who made self-incriminating statements about the killings. She was arrested on May 5, 2015, and Samson-Richter was arrested the next day.

'This went terribly wrong'

Before he was sentenced Tuesday, Samson-Vonrichter read a handwritten letter in court.

"I want to apologize for what happened. I cannot ever live with myself without saying I'm truly sorry for the heartbreak and distress I caused," he read.

"I wanted to scare Travis and wanted to get my things back, but this went terribly wrong. I wish I could go back, but I can't now," he said.

"I hope someday you find it in you to forgive me for the pain and heartbreak."

As he left the court room, Samson Vonrichter told the family, "I'm sorry again!" One person answered, "It's too late for that," then swore at him.

René Samson Vonrichter and Sonia Vilon arrive at the Gatineau courthouse on Tuesday, where they pleaded guilty to the 2014 killings. (Ashley Burke/CBC)

Victim's mother reads impact statement

About two dozen relatives of Trottier were in court for the proceedings Tuesday, including her parents, Victoria Lebrasseur and Claude Trottier. Other relatives reacted emotionally as Victoria Lebrasseur read a victim impact statement to the court.

"We walked into a nightmare that most people only see on a horror movie to find Amanda and Travis in a pool of blood — the worst day of our life," Lebrasseur told court. "A parent's nightmare. I was in total shock, screaming, 'No, no, no!' Falling to the ground. Shaking so much."

She described the next few months as "a fog." The couple had trouble eating and sleeping, and felt "numb and in disbelief."

A lot of tears & sniffles from Amanda Trottier's family in court when her mother read out this emotional letter about her heartbreak <a href="https://t.co/My4B77JrkP">pic.twitter.com/My4B77JrkP</a> —@AshleyBurkeCBC

Votour's aunt, Christine Votour, also read a victim impact statement in court Tuesday, saying he had a "kind heart."

"You took the lives of two young adults who were raising a child.... Now there is a child without a mom," she read aloud. "This is all because of you. I hope and pray you get the maximum sentence for the death of my nephew Travis."