The grandparents of murdered sisters Celeste and Bella Watts opened up about their heartbreak at learning they would not get to see the girls before their were buried during an interview with Dr Phil.

'We got permission from [Watts'] side of the family to have the grandchildren and bury our grandchildren with their mom,' said Shanann Watts' father Frank Rzucek.

'But the hardest thing was flying them here, because they were in crude oil for four days. So they were flammable. So we couldn't cremate them. They would have blown up a building.'

He continued: 'They had to have a bigger coffin and then they had to seal it with a certain wrap, so the gasses wouldn't leak out. That's pretty sad, isn't it? So we three here never got to say good-bye to our family or see them.'

His wife Sandy then added: 'Never got to hug them. Never got to say "I love you" like most people do.'

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Speaking: Frank Rzucek and his wife Sandy (above) spoke about the deaths of their daughter, granddaughters and grandson-to-be on The Dr Phil Show this week

Murders: Bella, 4, and Celeste, 3, were dumped in two separate oil tanks after they were suffocated by their father (above with mom Shanann a few months before the murders)

Recovery: Chris dumped the bodies of Celeste and Bella into oil tanks and buried Shanann in a shallow grave (officials removing the bodies of Celeste and Bella)

Final resting place: Shanann's mother Sandy explained: 'Never got to hug them. Never got to say "I love you" like most people do' (Celeste, Bella and Shanann's grave above)

The process of removing the girls' bodies from massive oil drums began at 5am on the morning of August 16, and would go on for almost 14 hours, with a report noting that at 6.45pm that evening members of the Colorado State Patrol cleared the scene.

In that time, the oil from the two 400-barrel tanks on the scene were manually drained by workers, who carefully poured the liquid over metal screens to collect any possible evidence.

Then, once the tanks were emptied, men in self-contained breathing gear entered and removed the bodies of Bella and Celeste, whose skin came off their bodies as they were passed out of the tanks.

Their mother and unborn baby brother Nico were found just 100 yards away in a shallow grave.

The report reveals that the diameter of the oil tank's opening was only 8 inches, meaning it would have been too small to fit Shanann's body.

The troopers who headed up the retrieval process arrived on the scene around 9am on the morning of August 16.

'While the first crude tank was being off-loaded, Trooper Bandy, Reeder and I put rope handles on two containment pools,' wrote Tropper Wilson.

'We anticipated the bodies to be covered in crude oil and were going to use the pools to put each body in, once recovered.'

Once the tanks were emptied, the bolts on the tank doors at the base of the barrel were taken off by the team on the scene.

'Sergeant Armstrong went up to the top of the tank and looked in the thief hatch,' states the report.

'Sergeant Armstrong told me he could see what looked like a body face down on the south side of the tank.'

Photos were taken and then the men began the process of removing the body from the tank.

Because of the level of oil sludge and toxic fumes, the men could only remain in the tank for a matter of minutes, making the process that much more complicated and difficult.

'Trooper Reeder went in first then me close behind. There was a body face down on the south side of the tank with the head facing west. It appeared to be a small female child,' reads the report.

'Trooper Reeder grasped the upper portion of her right arm to turn her over. Trooper Reeder then lifted her by both upper arms as I held her right leg. Trooper Reeder held her left arm and left leg as we moved the body towards the manway.'

The victim was then moved out of the tank, but during the process hand her hand 'degloved' of its skin.

That skin was retrieved and given to a member of law enforcement on the scene.

Behind bars: Watts was moved to the Wisconsin Department of Corrections after threats were made on his life (above in his Colorado mugshots)

Caught: Watts watches himself load the bodies into his truck on a neighbor's surveillance camera

The men next went about removing the body of the second victim, which was found in the second oil tank.

'I grabbed her right arm near the wrist area and moved her towards the manway. At this point, Trooper Reeder was able to secure her left arm and left leg. Trooper Reeder and I then passed the body through the manway,' reads the report.

'Trooper Bandy grasped the left wrist and shoulder area as Sergeant Armstrong did the same on the right side. As the victim was passed through the manway Trooper Bandy and Sergeant continued to support her body as she was placed into a containment pool.'

The report also notes: 'During this extraction there was some skin slippage where we had to touch the victim’s body. There was also some skin on the plywood where her back made contact.'

Some skin was also lost while the body was being moved to the oil pool.

'There was also some skin on the plywood where her back made contact,' reads the report.

'Trooper Reeder and I then walked around the inside of that tank which also had approximately 4” of crude sludge in it. We did not locate any additional evidence in tank. We exited the tank and walked over to the field south of the tanks. The body was turned over to the Weld County Coroner.

'Sergeant Armstrong continued to monitor the second victim, using a four-gas monitor, as the Weld County Coroner and Pathologist attempted to remove the crude oil utilizing several oil absorbent pads.

'The second victim was then placed into a body bag and taken to the Weld County Coroner’s vehicle.'

Bella was 4 and her sister Celeste had just turned 3 at the time they were murdered by their father.