A post-mortem examination carried out on the body of Jane Rimmer almost two months after her disappearance from Claremont found a bone was missing from her neck, according to a former senior member of the Macro police task force.

Key points: Ms Rimmer's body was badly decomposed when it was found south of Perth

Ms Rimmer's body was badly decomposed when it was found south of Perth She was one of three women who disappeared from Claremont in the 1990s

She was one of three women who disappeared from Claremont in the 1990s Lawyers are scrutinising forensic procedures used in examining the cases

Bradley Robert Edwards is accused of killing Ms Rimmer, 23, Sarah Spiers, 18, and Ciara Glennon, 27, but denies the murder charges against him.

His marathon Supreme Court trial has now entered its seventh week, but is expected to continue for several months as it sifts through mountains of evidence.

Superintendent John Leembruggen, who is currently in charge of WA's police air wing division, spent two years in the 1990s working for the Macro Task Force — the police unit set up to investigate the string of Claremont disappearances.

The then detective senior constable was also the officer who liaised directly with the Rimmer family during the early phase of the investigation.

Ms Rimmer's badly decomposed body was discovered in bushland in Wellard, south of Perth, 55 days after her disappearance from Claremont in June 1996 and was taken to the state mortuary, where forensic pathologists performed a post-mortem examination.

The day after the autopsy, Superintendent Leembruggen went back to the scene in Wellard to inform forensic police of what the pathologists had found.

Bradley Robert Edwards denies committing the crimes known as the Claremont serial killings. ( ABC News: Anne Barnetson )

He told the court Ms Rimmer's hyoid bone, found in the neck, was missing and that he had passed that information on to his police colleagues who were conducting a search of the area.

Telstra knife mystery

Superintendent Leembruggen also went to Greenacres Riding School, close to where Ms Rimmer's body had been found, where he seized a knife that had been discovered by a man riding a horse on a track nearby.

A Telstra-issued knife with an embossed logo was found near where Jane Rimmer's body was discovered in Wellard. ( Supplied: Supreme Court of WA )

The court has previously heard the wooden-handled pocket knife was Telstra-issued.

As a result of that find, the officer contacted telecommunications providers to find out whether any recent work had been undertaken in the Wellard area.

Superintendent John Leembruggen spent two years in the 1990s working for the Macro Task Force. ( ABC News: Hugh Sando )

However, he told the trial those enquiries were short-lived.

"We rang Telstra and Optus to see what they might have done," Superintendent Leembruggen told the court.

"They provided us with some maps and information and no further enquiries were arising."

'People are going to be astounded'

Superintendent Leembruggen also went to the crime scene where Ms Glennon's body was found on April 3, 1997, along with David Caldwell, a police investigator from South Carolina who had experience in serial killings.

Back in 1997, before anyone had been charged over the disappearances of the three women, Mr Caldwell held a press conference offering his insights into the type of person he believed could have committed the Claremont murders.

"This person is probably very bright, very much in control of himself, has all of the outward appearances of a very stable person," Mr Caldwell said at the time.

"This is probably a very pleasant, normal-appearing person.

"I daresay that when this guy is arrested, I guarantee that people are going to be absolutely astounded.

"They're going to say, 'I worked with this guy. He's my next-door neighbour. Surely it can't be?'"

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 3 minutes 59 seconds 3 m 59 s A timeline of the Claremont serial killings

Technician quizzed on DNA knowledge

The trial also heard from another mortuary technician who assisted in Ms Glennon's post-mortem examination.

Graham Paul took the court through his processes as he assisted forensic pathologists with their examinations of Ms Glennon's body.

Mortuary technician Graham Paul leaves the Perth District Court after giving evidence at the Claremont serial killer trial. ( ABC News: Charlotte Hamlyn )

He was shown video footage of the post-mortem examination which showed him cleaning debris from his glove with a sponge that had been earlier been on the floor.

Defence lawyer Genevieve Cleary asked Mr Paul about his familiarity with DNA technology back in the 1990s.

"It would be fair to say in 1995, 1996 and 1997 you didn't know you could leave DNA on a body by touching it?" Ms Cleary asked.

"There's always a chance of cross-contamination," Mr Paul said.

"But to what extent … I think there was just limited knowledge."

The trial continues.