DETECTIVES investigating the deaths of three children and their father at a beauty spot have recovered a knife.

The bodies of Sam Fuller, 12, and his sisters Becka, aged eight, and seven-year-old Charlotte, who was known as Charlie, were found in isolated woodland yesterday. It is believed they died from knife wounds.

The body of their father former Huddersfield University student Ceri Fuller, 35, was found nearby at the Poles Coppice on Pontesbury Hill, near Shrewsbury, Shropshire. He is thought to have fallen from a cliff.

West Mercia detectives have launched a murder investigation but described the deaths as a "tragic family situation" and are not looking for anyone else.

Detective Chief Inspector Neil Jamieson, who is leading the investigation, said: "I can disclose that a weapon has been recovered from the scene.

"Officers involved in the search found a knife in the vicinity of where the bodies were found.

"It will now be forensically examined."

Mr Jamieson said the old quarry and surrounding woodland would remain cordoned off as officers continue a detailed search of the area.

Post-mortem examinations will be conducted this afternoon by a Home Office pathologist and may not be concluded until tomorrow, the detective confirmed.

Police are appealing for information about possible sightings of the vehicle and its four occupants on Thursday.

Mr Jamieson said: "We believe this vehicle left Gloucestershire at some point last Wednesday evening or early Thursday morning and we are anxious to establish its movements since then, especially in the Pontesbury area.

"We believe it was in the Leominster area at around midday on Thursday before making its way up towards Welshpool later that day."

He said several people have already come forward with helpful information that would help police track the vehicle’s movements.

"This is in response to our appeals and we are grateful for their assistance," he said.

"However, I am still urging people to call Shrewsbury police station on 101 or our other number, 0300 333 3000, with any details which could help the investigation."

While police work continues in Shropshire, a team of West Mercia detectives have travelled to Gloucestershire to make further inquiries, including speaking to family members.

"We are working very closely with our colleagues in Gloucestershire to try to establish the full circumstances leading up to this tragedy," Mr Jamieson added.

Officers found the bodies of the Fuller children shortly before 10am yesterday. The family Land Rover Freelander was discovered nearby.

University graduate Mr Fuller and the children had left their home at Milkwall, near Coleford, Gloucestershire, last Thursday.

Becka and Charlie were pupils at St John’s Church of England Primary School in Coleford, which older brother Sam had also attended before moving to secondary school.

Headteacher Jan Wagstaff said: "Rebecca and Charlotte were absolutely delightful children and a pleasure to have in school.

"Sam was also a pupil here before he moved on to Lakers. He was a lot of fun and always had a ready smile. They will all be very sadly missed.

"Our thoughts and prayers are with their family."

Alison Elliott, head of Lakers School in Coleford, added: "We are desperately sad to hear the family are having to face such a dreadful situation.

"Sam was a well loved member of our extended family here at Lakers. Our thoughts are with the family at this very tragic time.

"We have arrangements in place to support students, staff, friends and family at this very difficult time."

Mr Fuller married his wife Ruth in August 2009 and neighbours said they had lived in a cream pebbledash semi-detached home on Station Road in the village of Milkwall for about a year.

Neighbours said the family "kept themselves to themselves" but spoke of their shock.

Janice Ayres, who lives next door to the Fuller family, said: "Very, very sad, I just cannot say any more.

"I didn’t even know her name (mother of the children). I have children of my own and I would just be devastated.

"I am surprised. They kept themselves to themselves. It’s so sad for three young children.

"Being out at work all day you don’t really know your neighbours. We would speak if we saw each other in the garden but we never socialised together.

"They were no trouble at all. They’ve lived here about a year and as far I know they bought the house as we knew the man who lived there before and he was selling it.

"It is dreadful really to think about it. It’s the way life is these days. You just live your own life."

Another neighbour, who did not wish to give their name, added: "They hadn’t lived here all that long. They kept themselves to themselves."

Rachel Annis, whose daughter went to the same school as Charlotte, told 5 News: "Charlotte was in my daughter’s class at St John’s. She was just a beautiful little girl. (They were) such characters.

"Sam would often come round and play with my son and so would Charlotte who was in my daughter’s class.

"She just had an angelic face, such a little angel."

Mrs Fuller’s father, Ron Tocknell, from Lydney, Gloucestershire, appealed for information when his son-in-law and grandchildren disappeared.

He wrote on his Facebook page: "If anyone who knows Ceri has any idea of his whereabouts, please contact Glos. police immediately. We are all so worried."

Mr Fuller worked as a production superviser at the Lydney-based Glatfelter paper mill, having joined in 2002.

According to his LinkedIn profile, Mr Fuller was educated at Whitecross School in Lydney before taking A-levels in physics, chemistry, biology and general studies at the Royal Forest of Dean College.

He then completed a BSc in molecular and cellular biology at the University of Huddersfield, graduating in 2001.

Mr Jamieson added: ``One line of enquiry being considered is that the father took the children's lives before taking his own.''