Forensic scientist Peter Hau said samples of Steve Wright's DNA were found on the bodies of Paula Clennell, Anneli Alderton and Annette Nicholls. He told the jury these were not likely to have come from "casual" encounters.

"I would say it would be more likely to be a prolonged, physical contact," Dr Hau said.

Prosecutor Peter Wright QC, asked if this applied to all three women. Dr Hau replied: "Yes, indeed."

Forklift truck driver Wright, 49, of Ipswich, denies murdering Miss Clennell, 24, Miss Alderton, 24, Miss Nicholls, 29, Gemma Adams, 25 and Tania Nicol, 19. His trial, at Ipswich Crown Court, is expected to last until March.

Dr Hau said Miss Nicholls was covered "extensively, from top to toe" in DNA linked to Wright. And he said it was virtually beyond doubt that DNA samples found on Miss Nicholls, Miss Clennell and Miss Alderton belonged to Wright.

"It is estimated the chances of matching a profile by chance is in the order of one in a billion," he said.

Dr Hau said unidentified "low level" DNA had also been found on the bodies of Miss Clennell, Miss Alderton and Miss Nicholls. But Wright's DNA was the only "common denominator" found on each of them, he said.

Dr Hau said tests had found no link with a man called Tom Stephens, who jurors had previously been told knew the five victims.

The jury of nine men and three women heard that much of the DNA was likely to have been washed off the women by the time they were found. The naked bodies of Miss Alderton, Miss Clennell and Miss Nicholls were discovered in woodlands after being missing for between two and seven days.