Fire definitely started in the kid's bedroom;
police allege due to a radiant electric heater known to be left on
at the foot of the bed (suspect a pillow/duvet was knocked down onto it).

Five fatalities, all found trapped in the lounge (house was like Fort Knox);
sole survivor pulled from a bathroom by a neighbour (who cut it's burglarproofing with a angle grinder).

Whole debate on why mommy & kids died despite discovering fire whilst on bed only.
Timeline based on the sole survivor (i.e. suspect)'s recollection.
Premise of Arson based on some alleged domestic strife,
and fire chief's claim of unusually-quick (i.e. < 15 minutes) flashover.

Fire Cause & -Origin methodology...