Mystery has continued to persist around the disappearance of Susan Powell for the last decade, but a new NBC Dateline special will be airing a cache of evidence for the first time, hoping to shed light on what really happened to the Utah mother-of-two that fateful December night.

Susan, 28, was last seen at the home she shared with her husband Josh and their two sons in West Valley City on December 7, 2009. Josh claimed he had taken the boys on a midnight excursion in freezing temperatures and returned to find his wife had vanished.

Authorities initially focused their attentions to Josh, who after losing custody of his children during the investigation, blew up his house with himself and his young boys locked inside.

Though prior to his death Josh protested that he had no idea what happened to his wife that night, Susan’s father, Chuck Cox, believes otherwise, telling NBC the night before she disappeared he had, uncharacteristically, offered to make the family dinner.

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Susan Powell (left) was last seen at the home she shared with her husband Josh (right) and their two sons in West Valley City on December 7, 2009.

Josh claimed he had taken the boys on a midnight excursion in freezing temperatures and returned to find Susan had vanished

Though prior to his death Josh protested that he had no idea what happened to his wife that night, Susan’s father, Chuck Cox (above), believes otherwise, telling NBC the night before she disappeared he had, uncharacteristically, offered to make the family dinner.

In a clip obtained exclusively by DailyMail.com, Cox recalls the moment he found out about the unusual gesture, believing Josh to have seized upon the opportunity to poison Susan.

‘When I heard that Josh had fixed them pancakes for dinner and put the pancakes on each person's plate, and then cleaned up the dishes immediately afterwards, I mean I just get chills down my back.

‘I've seen how he treated her in the house. I've seen how much he cares to help with dishes or cooking or anything.’

When asked if Josh cared at all to help his wife with domestic chores typically, Cox simply replies: ‘Not at all. Absolutely not. That was so out of character that it was just - that was scary.’

But Josh wasn’t the only Powell family member thought to have played a part in Susan’s disappearance and suspected murder.

Neither Josh, nor anyone else was ever charged in relation to the case, however his brother, Michael, and father, Steve, were both heavily suspected by investigators of having played a role.

In a clip obtained exclusively by DailyMail.com, Cox recalls the moment he found out about the unusual gesture, believing Josh to have used the opportunity to poison Susan

‘When I heard that Josh had fixed them pancakes for dinner and put the pancakes on each person's plate, and then cleaned up the dishes immediately afterwards, I mean I just get chills down my back. ‘I've seen how he treated her in the house. I've seen how much he cares to help with dishes or cooking or anything.’

Though neither Josh, nor anyone else was charged in relation to the case, his brother, Michael (left), and father, Steve (right), were both heavily suspected by investigators

Michael was first suspected by police in 2011, when it was discovered he had paid to have his car towed to a salvage yard two weeks after Susan vanished.

The 1997 ford Taurus was recovered from the Lindell Auto in Pendleton, Oregon, where authorities conducted forensic tests.

A cadaver dog indicated the presence of human decomposition inside the vehicle’s trunk, however DNA tests came back inconclusive.

Investigators from Utah visited Michael at his home in Minneapolis that October to interview him about the discovery and probe as to whether it had been used to transport Susan’s body from the home.

However, former detective Ellis Maxwell says he refused to answer any questions.

Two months later her contacted satellite imagery Apollo Mapping to obtain aerial images of Pendleton, Ohio, making specific mention to Lindell Auto Salvage yard.

He was told by the company they could only acquire a partial photograph of the yard, which Michael expressed interest in buying.

Police theorized that Josh(above) had killed Susan, and that Michael assisted in helping him to dispose of the body, but they didn’t have enough evidence to file charges against the brothers.

The home Susan shared with Josh in West Valley City, Utah, is pictured in 2010

Police theorized that Josh had killed Susan, and that Michael assisted in helping him to dispose of the body, but they didn’t have enough evidence to file charges against the brothers.

Michael was fiercely outspoken in denying his brother’s involvement in Susan’s disappearance, telling People that his brother was ‘grief-stricken’, and police time would be better spent looking for a suspect outside of the family.

‘As someone who is close to Josh, I know he is hurting because he misses his wife, and my hope for him is that people are understanding of that,’ he told the outlet.

He later set up his own website to blast the local police department, accusing them of slandering ‘the Powell family through a bizarre effort to cover up endeavors on our part to aid in the search for Josh's wife’.

Michael also used the website to defend his father, who had been charged in an unrelated case with 14 counts of voyeurism and one count of possessing images of minors depicted in a sexually explicit manner.

On February 5, 2012, Josh butchered his two young sons with a hatchet, before igniting cans of gasoline and blowing himself and the boys up in a fiery explosion at his Washington State home

A Pierce County Sheriff's deputy and Graham Firefighters work around the smoldering remains of Josh's home on February 5, 2012

He accused the police department of planting the images, which depicted two of his neighbor’s children, however Steve was later found guilty of all counts.

They also discovered photographs of Susan Powell, some reportedly taken while she was undressed, in his possession.

On February 5, 2012, Josh butchered his two young sons with a hatchet, before igniting cans of gasoline and blowing himself and the boys up in a fiery explosion at his Washington State home.

Following the murder-suicide, Michael became ensnared in a legal battle with Susan’s parents regarding Josh and his son’s $1.5 million insurance policy.

Four months before his death, Josh listed Michael as the beneficiary instead of Susan, however courts denied Michael access to the money.

Over a year later, Michael committed suicide by jumping from the roof of a building in downtown Minneapolis.

Immediately after Susan's disappearance, Steven Powell claimed his daughter-in-law was in love with him. In July 2011 he announced that he planned to publish her private journal online. Her parents managed to get a restraining order

Immediately after Susan's disappearance, Steven Powell claimed his daughter-in-law was in love with him. In July 2011 he announced that he planned to publish her private journal online. Her parents managed to get a restraining order.

A month later, Josh Powell and his father went on national television to discuss the case. They claimed Susan Powell was promiscuous, emotionally unstable and suicidal, a claim her family denied.

Steven Powell said he had a flirtatious relationship with his daughter-in-law and believed they were in love.

‘People don't know that there are two distinct sides of Susan. She was very ... kind of an open person in a sexual way ... with the opposite sex,’ he said.

'Susan was very sexual with me,' Steve Powell told ABC's Good Morning America. 'We interacted in a lot of sexual ways because Susan enjoys doing that.'

'I'm still thinking she left. Hopefully they'll be able to find her at some point... We don't believe she's dead.'

Investigators would later find 17 spiral-bound notebooks, detailing Steve Powell’s (near left) disturbing sexual obsession with his daughter-in-law (right), in which he admitted he would regularly secretly record Susan and later watch the clips back to masturbate to

The Coxes defended their daughter and said it was Steven Powell who initiated unwanted sexual advances.

Investigators would later find 17 spiral-bound notebooks, detailing Steve Powell’s disturbing sexual obsession with his daughter-in-law, in which he admitted he would regularly secretly record Susan and later watch the clips back to masturbate to.

He also detailed how he would spy on Susan as she showered and used to the bathroom by placing a handheld mirror underneath the door.’

'The fact is, I can hardly control myself when it comes to her,' wrote Steve in one entry, questioning whether his obsession ‘might be considered sociopathic. I mean, who looks under the bathroom door with a mirror?’

He went on to explain that he’s ‘never lusted for a woman as I have for Susan,’ calling his love for her his ‘greatest problem’ and ‘greatest pleasure’.

‘I enjoy taking video shots of pretty girls in shorts and skirts, beautiful women of every age,’ Steve wrote in one excerpt about secretly videotaping women such as Susan. ‘I sometimes use these images for self-stimulation.’

Family escort the casket of Braden and Charlie Powell on February 11, 2012

Family members believe the two young boys were sexually abused by Josh over a series of years, prior to their murders

In the lead up to his arrest, police would discover hours worth of illegal home movies in which he tapped dozens of females – including an eight-year-old and 10-year-old girl who lived nearby – without their knowledge.

An audio tape was also recovered by police, in which Steve can be heard confessing his love for Susan eight years before she disappeared.

‘I am still convinced she loves me and is sexually attracted to me,’ Steve wrote after the disappearance.

Steve was released from prison in 2017 after serving five years for child pornography possession. He died aged 67 the following year after suffering a heart attack.

In announcing his death, the Pierce County Sherriff’s Office said, ‘We believe a lot of secrets died with him,’ in reference to Susan’s disappearance.

Dateline NBC with air its episode of Haunted this Friday, at 9:00pm EST / 8:00pm CT.

Presented by Keith Morrison, the new two-hour special will dig through private journals, home videos, and emails to help retrace Susan’s final days - and unearth a number of the Powell family’s dark secrets.