A team of scientists spent more than a year-and-a-half amassing forensic evidence which snared the alleged killer of Sarah Payne, a court heard.

Twenty lever-arch files were filled with hundreds of pages of notes by the team from the Forensic Science Service Laboratory in London.

Ray Chapman, who led the painstaking investigation, this morning told Lewes Crown Court, the group's first task was to formally identify Sarah's body when it was discovered in a field near Pulborough, 16 days after she had gone missing from a country lane 21 miles away in Kingston Gorse, near Littlehampton.

The court was then told the aim of the investigation was to discover any links between the eight-year-old schoolgirl and the man accused of her kidnap and murder, Roy Whiting, 42, formally of St Augustine's Road, Littlehampton.

Timothy Langdale QC, for the prosecution, told the court it was a "massive investigation".

Mr Chapman said Sarah's body was initially examined to see if any traces of Whiting's DNA could be found from blood or hair.

Then Sarah's shoe, found a few days after her body at crossroads near Coolham four miles from the grave site, was examined for fibres. More than 350 were found in the sandal's velcro strap.

These were compared with fibres found in items from the cab of Whiting's white van, seized by police on the day of his arrest.

Mr Chapman confirmed that among the 350 fibres checked, four were found matching threads from a red sweatshirt which had been lying in the van.

He also said one fibre from a clown-pattern curtain had been found in the van.

The court heard how the material was subject to a sequence of stringent chemical and physical examinations after being compared under a high-powered microscope.

Matching fibres were then subject to microspectro photometry, in which a beam of light is shone through the fibre through a computer which detects how much light of each colour is absorbed.

In the final test, dye is extracted from the fibre and separated into its constituent ingredients to analyse how it was manufactured.

Mr Chapman told the court the thread from the clown curtain was important because it was "particularly distinctive".

He said: "It starts off with a green colour then it becomes almost colourless. It starts to darken up and you have got a shade of grey or blue turning to black.

"It has also got a pink tinge to it. The vast majority of fibres are of one colour but with the curtain the colour has been printed on."

A solitary blonde hair matching the full DNA profile of Sarah Payne was also discovered on the red sweatshirt in Whiting's van.

Mr Chapman said the chance of that hair not being the eight-year-old's was "one in one billion".

He also told the court that a full DNA profile of Whiting had been obtained from the sweatshirt's cuffs and collar.

Mr Langdale asked Mr Chapman: "If that hair, the hair found on the sweatshirt with the full profile matching Sarah Payne's DNA, if that hair did not come from Sarah Payne then the DNA profile must have been matched by chance?"

Mr Chapman replied: "The chance of obtaining the match if that hair had come from somebody else would be in the order of one in one billion."

A total of 24 hairs found on the sweatshirt were analysed but only one gave a DNA match to the murdered schoolgirl.

Speaking of the testing of the collar and cuff of the sweatshirt Mr Chapman said it was common if the police wished to find out if a person had worn that article of clothing.

He said: "The police were interested in trying to show whether or not Mr Whiting had worn the sweatshirt.

"It's a fairly common thing to do. In some crimes an item of clothing is left behind and it's fairly common to extract the collar and cuff to try and get the DNA profile of the wearer."

A partial DNA profile of Whiting was also found on the socks that were discovered in his van.

Mr Chapman said that the chance of obtaining that match if the DNA did not belong to Whiting was one in 200,000.

He said that the profile was given by a saliva stain on the socks.

Mr Chapman added that five hairs from the green-checked shirt had been tested but no DNA profile could be found.

He also said that a saliva stain on the clown-patterned curtain found in Whiting's van matched the suspects DNA profile.

The trial continues.

28 November 2001