SECRET police recordings heard Mick Philpott whisper to his wife "I didn't mean to do it – on my life," the court has been told.
The covert surveillance, taken in a police van after the pair were charged with six counts of murder, also heard him ask her "you are definitely sticking to the story?" it was alleged.
And Philpott was also allegedly recorded saying that the judge "would need to have big balls because there is no evidence".
Detective Constable Martin Hare, giving evidence, said he had 12 years' experience analysing secret recordings and that more than 325 hours was recorded of the Philpotts.
These were taken while they stayed in the Premier Inn, in Uttoxeter New Road, following the fire, and in the police van on May 31 as they were being transported to Southern Derbyshire Magistrates' Court.
DC Hart said Philpott said to her: "You are definitely sticking to the story? I didn't mean to do it, on my life.
"I can't believe they are trying to blame you."
Mrs Philpott said: "I know."
Philpott asked her about her police interview.
She replied: "They said did you pour the petrol cos they said something about expert….thingy."
Asked how many times he and his colleagues listened to that section of the tape, DC Hare said "hundreds of times".
He said: "Not until we were 100% satisfied that is what Mick Philpott had said did we submit it to the court."
Anthony Orchard QC, for Philpott, said the defence disputed the six words "I didn't mean to do it" that the father-of-17 is alleged to have whispered.
He brought his own expert to give evidence, Dr Martin Barry, a forensic speech analyst with 21 years' experience. Dr Barry said he used a specialist piece of equipment called a spectrogram to analyse speech patterns.
Mr Orchard said: "How many times have you listened to that section?"
Dr Barry said: "Several thousand."
Mr Orchard asked: "Did you find any of those words?"
Dr Barry said: "Not in that transcript, no."
Other sections of the covert recording that are not disputed were also heard in court.
In one, Philpott told his wife: "My brief said that for the judge to do what he's doing he's got to have some balls, big balls, because there is no evidence.
"They have got nothing, there's no petrol on my trousers.
"We have got nothing to worry about, just stick to what we said."
Philpott also advises his wife to be careful when she is in prison awaiting the trial, telling her not to talk to anyone.
He said: "Just listen, when you get to prison, don't talk to nobody, don't talk to any prisoners about it.
"It is the word of Adam, Vicky and Shakey (two neighbours and co-accused Paul Mosley)."
*THE PHILPOTT TRIAL: Visit our Philpott trial channel here for all related stories in the fire death case.