Tests were being carried out last night to establish whether a third body found in the charred rubble of a businessman’s mansion was that of his missing 15-year-old daughter.

Kirstie Foster has not been seen since the rambling manor house in the Shropshire commuter belt was destroyed in an arson attack a week ago.

A murder inquiry began on Sunday after bodies of the businessman’s wife, Jillian Foster, 49, and that of an unidentified man, believed to be her husband, Christopher, 50, were found. His .22 rimfire rifle was found near by.

Mrs Foster was killed by a shot to her head, prompting speculation that her husband murdered his family, and their dogs and horses before setting fire to the house. The police are keeping an open mind about the events that led to the deaths and have not discounted the possibility that the murderer went to extraordinary lengths to stage a suicide-murder scene.

It is known that Mr Foster, a flamboyant character, was under enormous strain from his collapsing business empire and mounting debts. His company, Ulva Ltd, which supplied insulated pipes to offshore oil-rigs, had gone into liquidation and the bailiffs were due to call at his home.

West Mercia Constabulary called in a forensic archaeologist to help searchers to remove human remains from one of the most badly damaged parts of Osbaston House in Maesbrook, near Oswestry, and to help to reconstruct the events, in precise sequence, leading up to the deaths.

Detective Superintendent Jon Groves, leading the investigation, said that the search could take weeks: “We had the remains confirmed as human by a Home Office pathologist and work has now begun to extract the body. Due to its position, it will take some time to remove.” Ian Hanson, senior lecturer in forensic archaelogy at Bournemouth University, said that the specialist would look at the deposits above and below the body to come up with a sequence of events. He said that they would apply the principles of geology to a modern day crime scene: “It does not matter if the deposits came to rest five minutes ago or 5,000 years ago. The principles are the same: what is above is more recent than what is below.”

A pall hung over Maesbrook, a village of tidy bungalows, gated neo-Georgian townhouses and a few wealthy householders who live, as the Fosters did, in substantial homes largely hidden from view.

Ann Parr, landlady at the Black Horse pub in the heart of the village, said: “In one sense Kirstie is the biggest victim in the whole tragic affair. Whatever her father and mother did or knew, she was just a 15-year-old girl with her whole life to look forward to.”

Megan Bray, 15, said to be Kirstie’s best friend, wept as she laid a bouquet near Osbaston House. Megan, a fellow pupil at the £16,500-a-year Ellesmere College, was with her mother. The tribute read: “Who is going to entertain me at Talbot Diner any more? It was not your time to go and I will never forget any of you.”

Photographs on Kirstie’s favourite social networking website, Bebo, show her on school trips, at parties and taking part in pony shows with her horses, Scrumpy Jack, Breezy and Bramble. The horses were shot and killed, along with the family’s dogs.

Ian Coe, 43, a farrier who worked at the house only days before the blaze, described the Fosters as a “happy, wonderful family” who had given no indication of anything untoward.

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