The force was legally required to refer itself to the Independent Office for Police Conduct (IOPC) in the aftermath of Carl Whalley's death in Clayton-le-Woods near Leyland in mid-October because officers had spoken to him shortly before he died.
Now the IOPC has referred the matter back to Lancashire Police and asked them to carry out a "local investigation" into the case and compile an official report about the actions of the force in responding to Mr Whalley's complaints, which included claims of a neighbour dispute.
Only last week, following a three-month probe into the cause of the blast, the force concluded there were no suspicious circumstances and no evidence of third party involvement.
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A melted plastic petrol can was found behind the front door of the semi-detached dormer bungalow in Kirkby Avenue and traces of an accelerant were also discovered on lounge curtains.
Mr Whalley, who was believed to have been in an upstairs bedroom when the inferno erupted, died from smoke inhalation and burns. His body had to be positively identified from DNA.
A spokesperson for Lancashire Constabulary said: "We have now completed our investigation, which involved some really complex and meticulous work, and we have concluded that there were no suspicious circumstances and no evidence of any third-party involvement.
"Mr Whalley’s family have been informed and our thoughts remain with them at this difficult time.
"The matter will now be referred to HM Coroner and will proceed to an inquest."
The Lancashire Coroner has now scheduled a full hearing to be held in Preston on Tuesday March 8.
An IOPC spokesperson said: “We received a mandatory referral from Lancashire Police following a fatal fire at a house in Clayton-le-Woods on 15 October last year, due to the fact officers had contact with the occupant prior to the incident.
"Our thoughts remain with all those affected by this tragedy.
"After assessing the available information we directed the force to carry out a local investigation."
The tragedy happened around lunchtime on Friday October 15. The fireball which ripped through the house completely demolished it and badly damaged the adjacent semi next door.