Cable ties used to bind the hands of British backpacker Joanne Lees were contaminated by a forensic scientist, a court in northern Australia has heard.
Joanne Lees gave evidence earlier in the trial
The cuffs were allegedly used by Bradley Murdoch, 47, who is accused of killing Miss Lees' boyfriend Peter Falconio, 28, during an ambush in 2001.
He denies murder and the assault and kidnap of Miss Lees, 32, of Brighton.
Forensic biologist Carmen Eckhoff told the court laboratory director Dr Peter Thatcher's DNA was found on the cuffs.
She said the presence of his DNA on the "significant" piece of evidence could have got there in a number of ways, despite protocols being in place to prevent it happening.
During cross-examination by defence lawyer Grant Algie, Ms Eckhoff said she did not know how Dr Thatcher's DNA came to be on the exhibit.
"I was not there when he was handling it, but I'm aware he was handling it on a number of occasions," she said.
On Friday defence barristers told the court that police may have contaminated the handcuffs, saying they were photographed next to tape found at the home of the suspect.
In other DNA evidence the jury heard on Tuesday that blood on Miss Lees' t-shirt was 150 million billion times more likely to be Bradley Murdoch's than any other local white male's.
It is alleged Mr Murdoch flagged down the couple's camper van on a remote highway in the Outback, shot Mr Falconio and attacked Miss Lees.
The court earlier heard Miss Lees escaped and hid "like a rabbit" for five hours in scrub, before being rescued.
Mr Falconio's body has never been found.
When asked in court on Wednesday about the cable bindings Ms Eckhoff said she asked Dr Thatcher - director of the Forensic Science Laboratory - how his DNA came to be there and that he provided an explanation. Prosecutor Anthony Elliott objected when Mr Algie asked what that explanation was.
He again objected when Mr Algie asked which protocol Dr Thatcher may have broken.
Mr Algie asked the prosecution to call Dr Thatcher as a witness later in the trial.
Ms Eckhoff said Dr Thatcher had the cable ties signed out to him on three occasions in 2001 and 2002.
During cross-examination Ms Eckhoff said she did not agree with the cable ties being taken to Yatala Prison in Adelaide, South Australia, where Mr Murdoch was on remand in October 2002.
Mr Falconio's body has never been found
"I was unhappy about them leaving my possession, particularly if the forensic examination may not have been completed."
She made her feelings known to Dr Thatcher, who gave the handcuffs to Senior Constable Tim Sandry so he could take them to Adelaide.
Earlier, Ms Eckhoff said that if anyone wanted to continue testing an item, such as the cable ties, it was "not ideal" to take them out of the laboratory.
But she said that if they remained in a sealed bag and were put in the same room as Mr Murdoch's items, or Mr Murdoch himself - as they were when police visited Yatala Prison - they would not be contaminated as long as the bag was not opened.
When asked about the possibility of deliberate contamination of the cable ties with Mr Murdoch's DNA she said that the samples from him that were stored in the freezer were of a very high concentration.
She said it was only possible to find DNA on the cable ties by using a method called "low copy number" because there was very little present.
The trial continues.