Darryl Manners showed Winchester Crown Court what he believed were mascara marks, a nose mark and a pink lipstick impression on a beige pillowcase found in the Turners’ home in Queenswood Avenue.

He said there were “no significant signs of smearing” and added that the pink substance on the pillowcase was similar in chemical comparison to what was taken in a swab from the 17-year-old New Zealander’s mouth.

In cross examination, Manners told Anthony Donne QC, representing Elliot Turner, 20, that he couldn’t tell the age of the marks on the pillowcase.

Another forensic scientist, Nicholas Oliver, told the court that he found the DNA of at least three people in an area of mucus on the back of Turner’s right shirt sleeve.

One matched Elliot Turner’s DNA profile, another was from Emily Longley, and the third wasn’t a full match, he said.

Oliver said: “In my opinion the DNA that matched Emily Longley is from the mucus. This is based on the strength of DNA components matching her.”

Elliot Turner is accused of strangling her in a jealous fit of rage at his parents’ house in Bournemouth, South England.

Medical witnesses told the court yesterday that Longley may have been strangled in a “sleeper hold” or suffocated with a pillow.

She showed no signs to suggest that her death was natural, the court heard.

Dr John Payne-James, who gave evidence at the court, also said a bruise on Turner’s left bicep was consistent with a sleeper hold.