Petrol was used to deliberately start a house blaze in which six children died, a fire investigator has told a court.
Mat Lee, from Derbyshire Fire Service, told Nottingham Crown Court the blaze at a house in Allenton, Derby, last May started in the hallway in front of the door and quickly spread up the stairs to the three bedrooms.
Mick and Mairead Philpott, and a third defendant, Paul Mosley, are on trial accused of the manslaughter of the Philpotts' six children, who died following the blaze at their house on May 11 last year. They deny the charges.
Mr Lee told the jurors: "The most likely cause of the fire was in my opinion the deliberate emission of petrol vapour by a naked flame or spark on the ground floor by a person."
Earlier the court heard covert recordings made in a police van taking the Philpotts to the magistrates court in Derby following their arrest 18 days after the fire. Philpott is alleged to have whispered to his wife during the journey on May 31: "You definitely sticking to the story? I didn't mean to do it. On my life."
But the comment was disputed by defence barristers. Philpott's barrister Anthony Orchard QC, argued that there was too much background noise for the comment to be heard clearly and disputed that his client made the comment "I didn't mean to do it".
Nottingham Crown Court has heard the Philpotts were being monitored 24 hours a day by Serious and Organised Crime detectives. In the van, Philpott is heard asking his wife: "Are we sticking to the story?" Mairead replies: "Hmmm". Mick whispers: "Good."
He then asks her: "Do you know something? Have they got any evidence on you? They've got nothing on me, nothing." Mrs Philpott is heard to say: "There's a fingerprint on the window." He replies: "That's it. A few discrepancies, that's all it is. One with Shakey (Paul Mosley) about I said I was going out for a drive at night. I can't remember saying that, Vicky said you were stoned and I said we didn't smoke."
Jade, 10, and brothers John, nine, Jack, eight, Jesse, six and Jayden, five, all died following the blaze. Their brother Duwayne, 13, was taken to Derby Royal Hospital and transferred to Birmingham Children's Hospital but died three days later. All six died from smoke inhalation, the court has heard.
The prosecution claim their deaths were the result of a "plan" to frame Philpott's former mistress Lisa Willis that went wrong. The trial was adjourned until Monday.