The court has heard that the petrol found on Mick Philpott's clothing didn't match the type found in his garden strimmer.
He has suggested that the petrol contamination on his clothing came from the strimmer.
Prosecutor Richard Latham has suggested to Mick Philpott that the reason he told police "the kids are in the back bedroom" rather than bedrooms is because he thought they would all be in Jade's bedroom.
Mr Philpott responds angrily to this suggestion, saying: "There you go again Mr Latham. It's just a phrase. It's your way of trying to twist things."
Mick Philpott's voice trembles as he says to the prosecutor: "Someone murdered my children and you are trying to blame me."
Prosecuting lawyer Richard Latham has accused Mick Philpott of ignoring a fire extinguisher because he had planned to "be a hero" by rescuing his children from a house fire.
Latham said Philpott intended to climb a ladder in the back garden in an escape planned before the fire. Philpott denies all the charges.
The trial has been adjourned and will resume tomorrow morning.
Mairead Philpott's barrister Shaun Smyth QC has asked Mick Philpott whether he had started the fire at the couple's Derby home while his wife was asleep in the conservatory.
"Did you start the fire or arrange the fire while Mairead was asleep?" he asked at Nottingham Crown Court.
Mick Philpott paused for a few moments before he said, sobbing: "I love my kids and I would never endanger them."
Mick Philpott has told the jury at Nottingham Crown Court that his wife Mairead Philpott and his ex-mistress Lisa Willis were lovers.
He told the court: "I didn't want to bring it out. But I'm being blackened here."
Earlier he had also paid tribute to his wife while admitting he had "never been a perfect father".
"Mairead is a perfect mother, a perfect wife, a perfect lady. She's kind, gentle & caring. I've never been a perfect father, I know that," he told the court.
Under cross-examination from Shaun Smyth QC, Mick Philpott denies that he regarded his wife Mairead as his 'property' or as a 'skivvy.'
When defence barrister Shaun Smyth suggests to Mick Philpott that as he was having sex with his ex-mistress, Lisa Willis, he didn't care about his wife Mairead. Mick Philpott replies: "it's hard for people to understand.
"No.1 is my mother. No.2 is my children. No.3 you can fall in love – and out of love – but you can't replace your children."
Mick Philpott tells the jury he had no suspicions that his ex-mistress started the fire at their family home on Victory Road, Derby.
Mick Philpott, continuing to give evidence at the Derby house fire trial, has described himself as a "caring loving father" who wanted his children back after his girlfriend Lisa Willis left the family home.
Speaking at Nottingham Crown Court on the 22nd day of the trial, he rejected the idea that he controlled the women in his life, having had simultaneous relationships with his wife and mistress under one roof.
Philpott said he did not want two women, but said you can't help who you love.
He earlier told the court: "For 10 years we were a happy family. My children were happy, that's all that matters to me."