A mother found strangled alongside her two young sons in a bed inside their Canadian home may have been a 'willing participant' in the events leading up to their deaths, a coroner's inquest has heard.

British Columbia investigators laid bare the chilling new details about the suspected family murder-suicide that led them to believe Janet Nguyen may not have resisted before she was killed by her husband, Christopher Duong.

Duong's body was also found in the same bed together with the couple's two young boys, aged two and four.

Royal Canadian Mounted Police Corporal Matthew Blumberg testified at the inquest that evidence at the scene led investigators to believe Nguyen was 'a willing participant.'

The devastating discovery was made on June 13, 2023, when authorities entered the family's Prince Rupert home and found all four family members dead together in a single bed.

'The children had teddy bears at their feet,' Blumberg testified, describing the moment officers realized the full horror of what had unfolded.

The inquest heard that their boys, Alexander and Harlan, died of asphyxia, with toxicology and physical evidence indicating they had likely been drugged prior to their deaths.

'The children were drugged prior to being murdered, based on the cold medication located on scene, being consistent with their toxicology results,' Blumberg testified, according to Global News.

Investigators said the boys showed no outward signs of violence.

'It was observed that neither of the children had obvious signs of injury, but their lips were blue and their skin was pale,' Blumberg told the hearing.

Authorities believe Christopher Duong killed his children.

Police also testified that Nguyen died after being strangled with an electrical cord.

'Janet Nguyen was strangled with an electrical cord to the point it was extremely tight; she could not have done that to herself,' Blumberg said.

Despite the violent nature of her death, investigators found no evidence that she fought back.

Blumberg also testified there was 'no sign of a struggle' between Duong and Nguyen.

Adding to the disturbing timeline, investigators discovered that the couple had recorded a video outlining their final wishes.

Blumberg testified that police found a 'last will and testament' video recorded on their phones, in which the couple detailed guardianship plans and their wishes for their property.

The video was recorded the same day Duong was detained by police under the Mental Health Act and released hours later.

Phone records also revealed troubling internet searches conducted by Duong before the deaths.

Blumberg testified that investigators found searches including 'painless ways to kill oneself,' information about dropping children off at a fire station and flight-related searches.

The inquest heard Duong believed he and his family were in danger in the days before their deaths.

Police testified Duong told authorities he feared a 'hit' had been ordered against him.

He was found driving his family around in an apparent attempt to avoid being tracked, prompting police to detain him under the Mental Health Act.

His doctor later testified Duong appeared 'very friendly and calm and co-operative' and did not raise immediate concerns during assessment.

But Duong's father told police his son had become increasingly paranoid and had taken his children into a parked car and stayed there for hours.

He also warned that Duong and Nguyen would 'amp each other up,' and that Duong would 'feed her the fear.'

Investigators told the inquest they found no evidence anyone else was involved.

'The evidence on scene did not indicate that there was any outside people involved other than the four decedents located in the crime scene,' Blumberg testified, reported CBC.

Police said they conducted a full investigation but determined the deaths were consistent with a murder-suicide involving only the family.

The family’s social media accounts painted a strikingly different picture from the horror investigators would later uncover. 

Photos showed a smiling family of four, with Duong and Nguyen posing proudly beside their young sons in affectionate vacation pictures. 

The parents appeared attentive and caring, while the children looked happy and secure, projecting images of a close-knit family that gave no outward signs of the fear and paranoia that would ultimately precede their deaths. 

Duong was known to police and had previously been linked to drug trafficking and weapons offences, the inquest heard.

He had also suffered a traumatic brain injury in a serious car crash about a year before the deaths.

The coroner's inquest, which does not assign criminal blame, is focused on establishing facts and identifying ways to prevent similar deaths.

The family was found dead just three days after Duong had been detained and released from hospital.

Social services had planned to make contact with the family but had not done so before their deaths.