Police have opened a murder inquiry into the death of a mother-of-five in a house fire started by a firework pushed through her door.

Mary Fox, 59 died after helping her teenage son Raum jump through an upstairs window to save him from the blaze.

Police today confirmed that the fire was started deliberately by a lit firework shoved through the letterbox or catflap of the house, in Carpenter Court, Bodmin, Cornwall.

They are investigating reports that Raum Fox, 17, was being targeted by local bullies, who were intimidating the family.

Launching a murder investigation this morning Superintendent Martin Orpe, of Devon and Cornwall Police, warned they would find those responsible.

He said: “As a result of a firework that was found late yesterday behind the door within the premises, and as a result of information from the public, this is being treated as a murder investigation.”

“I am appealing to those people involved in this to do the decent thing and come forward to the police.

“If not, I am confident from what I have seen that we will be knocking on their doors shortly.”

It is believed Raum suffers from mild learning difficulties and had recently moved schools to avoid bullying.

A number of names for those suspected of starting the fire have been posted on social networking sites since the arson.

Superintendent Orpe said police were now trying to separate genuine leads from local rumour.

He added: "This is a very serious incident. It seems there has been some bullying towards Raum in and around the school.

"That is an issue we will be looking at in depth as part of the inquiry. He is obviously very distressed at this time but he will be a critical witness in the case."

“This was not an address that we were called to a number of times and we do not have any evidence within police systems to corroborate that the family were being bullied and that this was reported to the police, but that is something that we will be looking at.

“We will be talking to partner agencies to tell us what they know about this family.”

Fire crews were called to the three-storey home at 7.15pm on Thursday after smoke was seen by a passer-by.

Thirty fire-fighters tackled the blaze but were unable to save Mrs Fox, who was trapped up stairs.

Raum had escaped through an upstairs window with his mother’s help.

He was taken to Treliske Hospital to be treated for smoke inhalation before being released.

A tribute page has been set up on Facebook for Mrs Cox, who also had four daughters, and her friends have started a petition calling for the regulation on Fireworks.

Steve Halstead, of Devon and Somerset Fire and Rescue Service, said: “Crews arrived at the scene to find a severe fire. There were flames already visible from the windows. “We were made aware that there was a person inside and crews made their way to the first floor, despite the severe fire and heat.

“Unfortunately the fire was fully developed and they found the casualty was already deceased.”

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