The Jodi Jones murder trial has heard that the teenager may have died when her throat was slashed from behind.
Jodi Jones was killed in June last year
Forensic scientist Derek Scrimger told the High Court in Edinburgh Jodi, 14, may have crawled or been dragged to the spot where she was found.
But he added that there was no evidence the attacker would have been bloodstained after the assault.
Luke Mitchell, 16, has denied murdering girlfriend Jodi and has lodged special defences of alibi and incrimination.
Mr Scrimger showed the jury photographs of bloodstains low down on a wall near where Jodi was found by a search party.
The court has heard how Jodi's grandmother and her sister were among those who discovered her body near the Roan's Dyke path in Dalkeith, Midlothian.
Mr Scrimger said the pattern of bloodstains was consistent with an artery being severed.
Blood was also found on sticks and the branches of trees in the area.
Mr Scrimger said: "Possibly the assailant would have been behind, standing for example."
"What many people fail to realise is that at the time of the assault there may not have been much blood there. There wouldn't necessarily be any blood on the assailant."
Under questioning from defence advocate Donald Findlay QC, Mr Scrimger admitted the police's handling of the crime scene was "not ideal".
He accepted that Jodi's body had been rolled onto a plastic sheet before forensic scientists had the chance to examine her and that Jodi had been exposed to overnight rain.
Earlier the court was told Jodi had her hands tied behind her back when her body was found.
Mark Heron, an identification officer with Lothian and Borders Police, said the 14-year-old was naked except for a pair of socks.
Items of clothing and a broken pair of spectacles were strewn around her.
The court was also shown a T-shirt in two pieces, trainers and the broken glasses, a lens from which was found separately.
Police also found a broken bra strap and a pair of trousers, with the legs tied in knots around Jodi's wrists.
Mr Heron told the court: "Basically her hands were behind her back."
He added that Jodi's socks had been pulled down on her feet so that they only covered her toes.
The murder charge alleges Luke Mitchell attacked Jodi, of Easthouses, Dalkeith, in woods near Roan's Dyke.
The youngster denies that and claims that at the time he was in, or near, his home, and that Jodi, 14, was murdered by person or persons unknown.
He also denies charges of possessing knives in public places and being concerned in the supply of cannabis resin to other school pupils, including Jodi.
The teenager has lodged the special defences of alibi and incrimination.
The trial continues.