THE foster parents of a young girl who was bludgeoned to death in her own home in a ''deranged'' attack told police yesterday they believed they had been plagued by a prowler in recent months.

Police have been seeking a scar-faced man after Billie-Jo Jenkins, 13, was found with horrific head injuries in her back garden in Hastings, East Sussex, on Saturday afternoon.

Her foster father, Sion, returned home with his 10 and 12-year-old daughters to find the foster daughter slumped in a pool of blood by the patio doors he had left her painting.

She had been beaten over the head with an 18-inch metal tent spike which had been lying nearby.

The murder weapon had been left in the back garden where the killer left the young girl with fatal head wounds.

Detectives described the at-tack as ''frenzied, deranged, and vicious'' and appealed for help in tracing a scar-faced man seen wandering around the area asking for accommodation earlier in the afternoon.

Billie-Jo's foster father, who is deputy headmaster of William Parker Secondary School in the seaside town, told detectives that just 12 days ago he had disturbed a man lurking in the rear garden of his house.

Weeks earlier, he had spotted a man standing in the park opposite the family home, staring at their house.

The family had installed security lighting around the home after they found the side gate open on several occasions since Christmas, making them believe someone had been prowling around the house.

Neighbours in Lower Park Road, where the girl lived with Mr Jenkins, his wife Lois, and their four natural daughters aged seven, nine, 10, and 12, spoke of a ''loving, caring girl'' who was devoted to the family bulldog Buster. She had fully integrated herself into the family, with a circle of friends at school and in the road.

She had remained in contact with her natural parents but had taken her foster family's surname.

The murdered girl had lived with her foster parents for four years and had moved with them from London to Hastings in 1993.

Her natural parents, who are divorced and live in Barking, east London, have been told of her death and are being counselled by police, who are also trying to find out more about her background.

Trained detectives were also with her foster family. They were said to be ''extremely traumatised'' and staying with relatives.

Detective Superintendent Jeremy Paine, who is leading the murder hunt, told a news conference: ''This was a vicious, ferocious attack on a young girl in her home.

''That is of enormous concern to us and everyone is working very hard to bring this offender to justice. It is vitally important that anybody with any information contacts the police immediately.''

Mr Paine said Billie-Jo was a ''joyful, loving'' girl, with no apparent problems, although they were talking to her family and teachers at Helenswood School, which she attended.

Mr Paine said: ''We know of no motive for the attack. There was no sexual motive. Billie-Jo was found lying where she had been painting the doors.

''She was hit on top of her head a number of times, causing severe injuries to her skull. It appears she had little opportunity to fight off her attacker.''

Neighbour Ann Webb, who lives next door to the Jenkins family, said: ''Billie-Jo was a young lady in the old-fashioned sense of the word. It is rare to meet a young girl nowadays with such manners and such an attitude. She was always polite, always caring.''

A fellow foster mother, Mrs Carol Crispin, 36, who lives further down the road with her two foster sons and a foster daughter the same age as Billie-Jo said: ''My children were friends with her and they are devastated.

''You wouldn't know she was their foster daughter, she was just one of the family. They all got on so well.

''When the family got their dog three years ago, Billie-Jo raced round here to show him off. She was always taking him for walks in the park.''

Mrs Crispin added: ''She was a lovely, bright, caring girl. She had a nice, tight circle of friends at school and in the area.''

Once a genteel holiday resort, the town has in recent years become inundated with DSS hostels, run-down bed and breakfast establishments and flats for patients released under the care in the community scheme.

Neighbours spoke of their concerns that part of their road was becoming run down and said there had been a recent spate of break-ins and vandalism in the area.

Neighbour Ann Webb said: ''This end of the road is nice and respectable but further down the houses have been converted into flats and bedsits. There have been problems and I know the Jenkins were broken into a couple of times a few years ago.''

Resident William Bates said: ''The authorities seem to have given up on this road. It was very nice a few years ago with all those big houses but it's going the way of the rest of the town.''

A police spokesman said that Hastings did have a problem with hundreds of hostels but the road in question was not known for specific problems.

However, only last year, a young man in his 20s was stabbed and beaten to death just a quarter of a mile away from Lower Park Road, and police recently installed a special box in Alexandra Park, opposite the Jenkins's home, after neighbours voiced concerns about prowlers around a wooded lake.

Detectives are looking at links between Saturday's murder and that of the stabbed man.

Police are also planning to ask Kent detectives for details about the deaths of Lin and Megan Russell, who were bludgeoned to death in Chillenden last July.

Last night, a single bunch of yellow roses in transparent wrapping lay by the rain-swept Hastings doorstep.

Two police officers stood guard.