Police sifting through the rubble of the fire-ravaged Osbaston House focused last night on the search for Kirstie Foster, 15, after one of two bodies found in the locked mansion was identified as that of her mother.

Jill Foster, 49, had been shot in the head before the fire was started. She was identified from dental records. The second body is that of an adult male and is thought to be Kirstie’s father, Christopher Foster, 50.

Kirstie is known to have been in the house, chatting to friends on her computer, at 1am on Tuesday, two hours before the fire at the £1.25 million Georgian mansion in the Shropshire village of Maesbrook, near Oswestry.

Police trawling through the rubble also found Mr Foster’s legitimately owned .22 rimfire rifle and the body of a dog near the human remains. It is not known whether the gun was used in any of the shootings.

Kirstie, a popular pupil at the £16,500-a-year Ellesmere College, was a keen horserider. It is believed that the murderer shot Mrs Foster and the dog before killing Kirstie’s three show ponies in the stable and a further three dogs housed in kennels, then started the fires, which broke out in the main house, the stable block and the kennels after 3am. Neighbours were alerted by the sound of an exploding car petrol tank an hour later.

The house is understood to have been barricaded from the inside and the window shutters closed and locked. Ammunition, described by the police as spent and unspent gun cartridges, was found scattered around the house and grounds.

West Mercia Constabularly said that it had begun a murder investigation but refused to be drawn on suggestions that Mr Foster broke under the strain as his business empire crumbled, killing his wife, daughter and family pets before setting fire to the property.

Mr Foster and his daughter are still considered by police formally to be missing.

The businessman, who cultivated his image as a member of Shropshire’s shooting and fishing set, is said to have flaunted his wealth, driving a succession of high-performance cars and indulging his daughter’s passion for horses. His company, Ulva Ltd, which supplied insulated pipes to the offshore oil industry, went into liquidation last year owing more than £1 million to suppliers and another £800,000 in tax. A Court of Appeal judge said that he was not to be trusted and was “bereft of the basic instinct of commercial morality”. Osbaston House, which he called his “dream home”, was under threat of repossession.

Mr Foster and his family attended a barbecue party and clay pigeon shoot thrown by a local car dealer on Bank Holiday Monday, which broke up at about 8.30pm. It is known that Mr Foster drank steadily, although he appeared happy and relaxed alongside his wife and daughter. The journey to their home was less than half a mile along quiet country lanes.

Detective Superintendent Jon Groves, of the West Mercia Constabulary major investigation unit, said: “Although this is now being treated as a murder, we are keeping an open mind as to the circumstances leading up to the incident.”

About 40 people from the area gathered for a special prayer meeting for the family at St John’s Church in Maesbrook. The Rev Prebendary David Austerberry told the congregation that the events had left everyone bewildered and stunned.

“It is hard to grasp what has happened,” he said. “It will be some time before everything is revealed and clear. Today we pray for the Fosters, their family and friends who must be devastated by the events of last Tuesday morning.”

The atmosphere among villagers was solemn. Speaking after the service, Mr Austerberry added: “A small community like this always supports each other and we will support each other and everyone who has been caught up in this.

“When we know what has happened perhaps there may be something more specific we can do. But at the moment all we can do is offer our prayers.”

Roger Doley, Mrs Foster’s brother, who lives in Wolverhampton, and his sister, Anne Goddings, were too upset to talk to the media.

The search at the house was delayed because the remaining walls of Osbaston House were beginning to lean inwards. Structural engineers returned to the site early yesterday to shore up the building so that the search could continue.

Police said that the search could take several days, possibly weeks, to complete.

Superintendent Gary Higgins, of West Mercia Constabularly, said that further tests were needed to establish the identity and cause of death of the second body. “Clearly we will be seeking to establish whether it is the body of Christopher Foster,” he said.

A postmortem examination revealed that the dog found near by had been shot. “The three horses and three dogs found in the outhouses had also been shot.

“Further tests are needed to estabish whether the rifle found was the one used in the murder and to kill the animals,” he said.

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