An inquest has heard that the children, aged three, four, six, and eight, died after a blaze broke out at their home in Stafford, Staffordshire. The tragic incident occurred on February 2, 2019, Daily Mail reports.

The parents, Natalie Unitt, 26, and Chris Moulton, 30, were detained on suspicion of manslaughter by gross negligence. Their arrest came after South Staffordshire Coroner Andrew Haigh found out that glass consistent with an ashtray was found melted into the springs of a mattress following the fire.

In August, the Crown Prosecution Service announced it was to take no further action, as there was not enough evidence against Ms. Unitt and Mr. Moulton.

However, on Thursday, November 12, an investigation revealed that Riley, Keegan, Tilly, and Olly, the four innocent children, died from “fumes from fire caused by [an] unextinguished cigarette” on bedding in the parents’ bedroom.

Fire investigator Leigh Richards said the blaze “was caused by carelessness with cigarettes.”

Furthermore, coroner Andrew Haigh stated:

“Ms Unitt had been advised not to smoke in the property but there is substantial evidence of them continuing to do so. It’s understandable they tried to play down the significance of this bearing in mind what has happened. Mr Moulton suggested that the fire may have been caused where the boiler is on the landing on the property. I do not accept that.

I have heard the expert evidence and Mr Richards has clearly indicated why the boiler is not the cause of this fire. He has properly explained his reasons for his decision as to the cause of the fire. That was that the fire started as a result of a cigarette on the bedding in the main bedroom.

Of significant note … within the recess of the left-hand (window) casement when looking from inside the lounge, there was a single discarded cigarette butt. That had not been stubbed out in my opinion and had been left to burn on its own. There was evidence within the lounge of a number of cigarettes that littered the carpet against the skirting boards.”

The only ones who managed to escape were Ms. Unitt, Mr. Moulton, and their youngest child, then two.

Both of the parents claim they can’t remember what happened after the blaze.

As per Richards, a fire officer, the accounts of the parents “was inconsistent with each other.” He declared:

“The fire in my opinion developed within the bedroom. As the fire developed, the room went into full flashover, where everything within the room becomes involved in fire. Having the windows open aided ventilation to the fire and allowed the fire to grow greatly and spread outside the compartment.The actions of Chris and Natalie remain a subject of conjecture.”

The mother of the children recalled smoking in bed and falling asleep before the fire.

When questioned about how she became aware of the blaze, Ms. Unitt said:

“I had heaviness on my chest. It was on the landing. I still have nightmares about it now.”

Mr. Moulton also confirmed he had gone to sleep after smoking in bed and that he was later awoken by the flames. He admitted he could not rescue the children as the “fire was too intense.”

According to the Crown Prosecution Service, there was insufficient evidence to bring charges against the couple.