A teenage boy critically ill in hospital after a house fire which killed five of his siblings is "unlikely to survive", police said.
Duwayne Philpott, 13, has been in hospital since the fire at the family home in Victory Road, Allenton, Derby, in the early hours of last Friday.
His sister Jade Philpott, 10, and brothers John, nine, Jack, seven, Jessie, six, and five-year-old Jayden died in the blaze.
Mike Philpott, back centre, with his children, wife and mistress
Assistant Chief Constable Steve Cotterill of Derbyshire police said: "Duwayne suffered serious injuries in the fire; tragically he is unlikely to survive.
"Mr and Mrs Philpott remain at their son's bedside and my thoughts are with them at this distressing time."
The children's father, Mick Philpott, who was dubbed "Shameless Mick" in 2007 for his benefit claims and refusal to get a job, in a documentary by former Conservative MP Ann Widdecombe, made a 'valiant' attempt to save them, police said.
On his wife Mairead's Facebook page, Mick suffered from angina and suffered from panic attacks - which she attributed to the stress caused from arguments with his mistress Lisa.
A 28-year-old woman and 38-year-old man, both from Derby, were arrested by officers investigating the deaths but were released without charge on Saturday.
ACC Cotterill added: "This investigation is still at an early stage and it should be stressed that we have not yet had the opportunity to speak to Mr and Mrs Philpott properly because they've been caring for their son in Birmingham."
"I want to thank the local community who have already come forward but I would urge anyone with any information, regardless of how insignificant you think it may be, to contact us.
"We would specifically like to speak to anyone who was in or around Victory Road between 3am and 4am on Friday morning."