Mr Yovich is going back over Dr Palmer's evidence from yesterday when he commented on a segment of Jane's hair being washed during her post-mortem.

Dr Palmer has shaken his head as he has watched a forensic pathologist pull vegetation out of the hair and drop it onto a drape on the floor.

His notes from watching the video include a number of exclamation marks and underlinings that Dr Palmer has agreed is indicative of the degree in which the processes fall short of "proper preservation practices".

In his notes from the recovery of Jane's body from bushland in Wellard, he commented "Individual with knitted jumper handling body!" and also agreed with Mr Yovich that he saw a forensic officer bagging vegetation from near the body into a bag with no gloves or protective clothing on.

Of Ciara's crime scene, he also commented, "No PPE!" in relation to the forensic officers.

He's agreed with Mr Yovich that it's possible the crime scene and post-mortem examiners could have contaminated Jane and Ciara's exhibits with fibres from their bodies or clothing.

"It's possible, I don't know if it would be a real possibility, but the risk exists," he said.

He's also agreed if contamination does occur, it is typical there are usually less fibres, with Mr Yovich referencing that only one blue polyester fibre was recovered from Jane and two from the shorts of Mr Edwards' rape victim.

Mr Yovich has provided an example to Dr Palmer, saying one of the forensic officers who attended Jane's crime scene drove a Holden Commodore station wagon, but couldn't recall the year it would have been made.

The officer, Sergeant Barry Mott, said he wore disposal overalls at the scene, which he retrieved from the boot of his vehicle and unwrapped from a sealed individual plastic bag.

Barry Mott Credit:9 News Perth

Mr Yovich has asked if Sergeant Mott could therefore be excluded as the source of the one rear cargo carpet fibre from a 1996 Holden Commodore VS station wagon found in Jane's hair.

Dr Palmer has said it couldn't be discounted, but given he did not have direct contact with the body, he would consider the scenario "less likely".

Dr Palmer has also agreed with Mr Yovich that the one blue polyester fibre found in Jane's hair could possibly have always been a single fibre, rather than remnants of many blue polyester fibres that were lost overtime when the body was exposed to the elements for 55 days, and the hair then washed during the post-mortem.

"That's a possibility, but given the situation, whilst it's possible, my own opinion it's less likely," he said.

Mr Yovich has now pointed out that no fibres from Ciara's clothing were found in Mr Edwards' former work vehicle when it was recovered 20 years after the murder.

Dr Palmer has said the failure to find any fibres was "not significant".