Chris Watts' young daughters Bella and Celeste are seen smiling for their mother in the last photo that was ever taken of the girls.

The images were snapped by their killer dad on his cell phone and sent to their mother Shanann, who was at a work conference in Arizona.

It was upon returning from that conference that Shanann was murdered by her husband, who buried her and their unborn baby boy Nico in a shallow grave on a remote oil field that was owned by his employer at the time Anadarko.

Watts then smothered his two daughters and dumped their bodies in an oil tank.

These photos and others from Watts' phone were obtained by DailyMail.com after filing a request under the Colorado Open Records Act.

Among those other images are a number of snaps taken by Watts' mistress Nichol Kessinger that he hid away in a secret calculator app on his phone.

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Photos found on Chris Watts' phone and obtained under an Open Records Request by DailyMail.com show the final images of his family (Shanann left; Bella just 12 hours before her death)

Other woman: Watts' phone also contained a number of images of himself and his mistress Nichol Kessinger

Baby girls: He took photos of his smiling daughters Bella (right) and Celeste (left)to send to his wife just 18 hours before her murdered them all

Kissing: Kessinger has said that Watts told her he was separating from his wife during the time the two were dating

News: Watts' home will go up for action on Wednesday, a little less than a year after he murdered his wife there in the bedroom to start a new life with Nichol (above)

Fees: The family purchased the home May 2013 for $392,709 but almost six years later still had an outstanding principal balance of $349,938.09

The home where the brutal murder took place is now up for grabs, just a few weeks before the anniversary of Shanann, Bella, Celeste and Nico's deaths.

The public auction of the Watts family’s $485,000 home was pushed to July back in April, just days before it was set to be offloaded to the highest bidder.

That move comes after Watts finally revealed to investigators just how he murdered his wife inside the home, before dragging her body down the stairs and loading her into his truck with daughters Bella and Celeste.

The decision to postpone the auction was made by the property’s new titleholder, JP Morgan Chase.

Watts was notified of the auction in a letter sent back in December by the Weld County Public Trustee.

Kessinger broke down in tears over the murders of Watts' family

Documents obtained by DailyMail.com show that Watts purchased the home in May 2013 for $392,709 but almost six years later still had an outstanding principal balance of $349,938.09.

The auction was never publicly announced in the local newspaper however, which is a requirement prior to any public sale in the state.

Then, early last week, the auction was halted, at a time when property prices are down in area.

The Watts’ home had been assessed at close to $550,000 at one time, but public records now put that number at $484,339.

Interested parties will now have to wait and see what the new date will be should they want to pick up the property.

They will then need to assemble at the office of the Weld County Public Trustee to place a bid.

Kissing: In love notes, Watts gushes about his mistress, saying that she 'heats him up' and 'cool me down like rain'

Murder mistress: Chris Watts was arrested for strangling his wife Shanann and smothering his two daughters at their home in Greeley, Colorado

Assisting: Kessinger spoke with police for two hours one day after Chris Watts confessed to the murder of his wife Shanann

Exposed: Investigators searched the phone on Kessinger with her permission, and uncovered a number of shocking Google searches

The felon's bride: Kessinger spent two hours searching the internet for wedding dresses a week before Chris Watts murdered his family

Shanann's family had been seen removing her possessions from home shortly after her death and then again once the trial was concluded.

Watts accepted a plea deal of life in prison after confessing to the murders. He is now behind bars in a maximum security prison in Wisconsin.

It was just a few hours after he buried the body of his wife and dumped his daughters in oil tanks that Watts' alibi began to fall apart.

That was due in large part to the surveillance footage his neighbor had of Watts on the morning of the murders, which very clearly showed him back his truck up to his garage, load up the vehicle and drive off.

Watts had told police and his wife Shanann's friends and family that she and daughters Bella and Celeste had run off that day while he was at work, but footage proved that was not the case.

In fact, the footage did not capture anyone leaving the house that day but Watts.

That was later refuted however by Watts himself, who said Bella and Celeste were alive when they left the home and murdered just before he disposed of their bodies in two oil drums on a job site.

In video obtained by DailyMail.com after filing a request under the Colorado Open Records Act, Watts is seen watching that video for the first time - and throwing his hands behind his head in disbelief when he realizes he has been caught.

That video would later be used to draw out Watts' confession before he was formally charged with murder.

Once he had confessed, the process began of retrieving the bodies of his wife and two daughters, who had been found despite his refusal to help with the search.