A pair of comic lounge pants revealed to police that a murder suspect may have had sex with the victim, a trial has heard.
Stephen Unwin and William McFall are accused of keeping Quyen Nguyen captive at a house for four hours, where prosecutors claim she was "raped and incapacitated" before she and her Audi A4 were dumped and set on fire at a dirt track in Shiney Row.
When questioned by detectives in the early stages of the investigation into the killing, Unwin told police he had known the victim but said she had been at his house for only half an hour on the night of her death and that they had no sexual of physical contact.
Forensic scientist Dr Mark Dale has told jurors at Newcastle Crown Court he examined a pair of long-legged Marvel lounge pants, which Unwin had worn on the night of the killing.
The doctor said he found DNA profiles matching Unwin and Miss Nguyen on the front inside section of the elastic waist trousers.
He told jurors: "The findings could be explained if Stephen Unwin had engaged in some form of sexual activity with the deceased before wearing the pants, without any underwear."
The doctor told jurors a small spot of blood matching Miss Nguyen's DNA profile was also found on the pants but there was no indication or suggestion of how it got there.
Dr Dale added: "The findings from Stephen Unwin's Marvel lounge pants are in keeping with the view he had engaged in sexual activity with the deceased."
The court heard there was no blood relating to the victim recovered from swabs taken from furniture, walls and objects within the house.
Dr Dale told jurors he examined a gas gun which was recovered from the house and had there was a "significant amount" of the victim's DNA found on the barrel.
The court heard the doctor had been asked to help identify Miss Nguyen's body after it was found in the burnt out car.
As part of the process, he tested a face-mask used by Miss Nguyen at the nail salon where she worked, as well as a tooth brush from her home.
He told the court: "The same female DNA profile was obtained from the mask and the toothbrush. This matched the DNA profile taken from the blood sample from the deceased."
Miss Nguyen's remains, which were badly damaged by fire, were found when emergency services were called to a dirt track at Success Road in Shiney Row, near Sunderland, after reports of a fire last August.
Unwin, 40, of St. Oswald's Terrace, Houghton, and McFall, 51, who is originally from Northern Ireland but now of Waterloo Road, Blackpool,both deny her murder and rape.
The trial continues.