Billie-Jo Jenkins was found on Saturday in the back garden of her foster parents' home in Hastings, East Sussex, where she had been painting the patio doors. She had been bludgeoned over the head with an 18in metal tent spike.
The 44-year-old man was detained as detectives released details of a scar-faced man they wanted to talk to about claims that Billie-Jo was being stalked.
The man, who lives in Hastings, was arrested at his home yesterday afternoon. Police said this followed media appeals for information about a man with a prominent birthmark stretching from his forehead to his chin.
A man was reported to have been wandering near Billie-Jo's home and asking for accommodation at about the time of the murder.
It emerged yesterday that the police were told Billie-Jo had complained of being followed by a stranger and of receiving nuisance telephone calls shortly before her murder.
Detectives revealed that her foster parents, Sion and Lois Jenkins, and friends, had told them she believed she was being followed since Christmas.
Mr Jenkins told detectives he disturbed a prowler in the back garden of the family home only 13 days ago and earlier saw a man staring at the house. Security lights had recently been fitted at the home.
However, it later emerged the foster parents did not contact police about the prowler or the nuisance telephone calls.
Billie-Jo had first claimed she was being stalked two years ago, when she started at Helenswood Secondary School in the East Sussex seaside resort, at the age of 11.
Police were informed about those claims and the school was made aware of the girl's fears.
Detective Superintendent Jeremy Paine, leading the murder hunt, said: "It is clear that Billie-Jo obviously believed she was being followed in the days and weeks before her death.
"She had told her parents and friends she felt she was being followed and had spotted a man on some occasions. She had also received a number of strange phone calls at her house.
"It appears that she felt this man was paying particular attention to her for some reason."
Detectives are also awaiting the arrival of a computer database from the investigation into the murders of Lin and Megan Russell in Kent last summer. In both cases the victims were attacked without apparent motive or sexual intent.
Detectives were yesterday continuing to interview both Billie-Jo's natural parents and her foster parents.
Billie-Jo was described as a popular, lively teenager with ambitions to become an actress. She enjoyed swimming and going to youth clubs.
Chris Luckin, headmaster of Blacklands Primary School, in Hastings, which Billie-Jo attended for two years before moving to secondary school, said: "We remember her as a delightful girl, interested in everything that went on in school.
"We are absolutely devastated by this tragic event. Children and staff are stunned and feel numb. We feel particularly for the other members of her family." Mr Luckin said staff at the 500-pupil school were in tears as the children were told of Billie-Jo's death. Three of her sisters still attend the school.Reuse content