Police today confirmed that the fire was started deliberately - they say petrol poured through the letterbox was used to start the blaze.
Five of Mick Philpott's children died after the fire broke out while they slept on Friday. His 13-year-old son Duwayne later died in hospital.
In tears, Mick Philpott spoke to the media in Derby five days after Jade Philpott, 10, John, nine, Jack, aged seven, Jessie, six, and five-year-old Jayden, all perished in the blaze.
Mr Philpott's 13-year-old son Duwayne died of his injuries in Birmingham Children's Hospital at the weekend.
Flanked by his wife Mairead, Mr Philpott told reporters about how Duwayne's organs had been donated for transplant.
They also thanked members of the local community for their "overwhelming" support since the tragedy.
The six children were asleep in their beds upstairs when the fire broke out at the semi-detached house in Allenton, Derby in the early hours of the morning.
Mr Philpott, aged 54, made a "valiant" attempt to save them, police said.
A 28-year-old woman and 38-year-old man, both local, were arrested by officers investigating the deaths but were released without charge on Saturday.
In a statement on Tuesday night, Derbyshire Police said officers were supporting Mr and Mrs Philpott and were in the process of speaking to them to understand the events of last Friday.
Assistant Chief Constable Steve Cotterill said: "It's important that we talk to Mr and Mrs Philpott about what happened.
"They have been through a traumatic incident we are giving them as much help as we can."