Gruesome details of 'bloodstains and jelly-like deposits' revealed as  double murder trial over missing secret lovers

•  READ MORE: All that remained of allegedly murdered campers

The trial of former Jetstar pilot Greg Lynn has been told of the forensic findings discovered at the alleged murder scene, as the hearing was suddenly adjourned.

Mr Lynn, 57, is facing trial in Victoria's Supreme Court after pleading not guilty to murdering secret lovers Russell Hill, 74, and Carol Clay, 73, on March 20, 2020.

The elderly couple vanished while on a camping trip in the remote Wonnangatta Valley, with their remains discovered more than 20 months later under a felled tree in bushland, the jury was told.

On Thursday, forensic officer Mark Gellatly told the jury he was asked to examine inside the canopy of Mr Hill's Toyota LandCruiser for the 'possible presence of blood' in February 2022.

In a compartment on the passenger side, he said he located six small 'apparent' blood stains and three 'jelly-like' fatty deposits.

He told the jury testing could not confirm the stains were blood, but his conclusion was it was 'most likely' blood, noting testing can return a false negative when heat-affected.

Testing of one stain and the fatty deposit but returned DNA samples with 'extremely strong support' for the proposition it originated from Mrs Clay.

Mr Gellatly said splatter analysis indicated 'some sort of forceful event' had occurred, but there wasn't enough information to make a finding on the mechanism.

'Excluding a freak gust of wind ... my best possible guess is the event occurred forward of this,' he said.

Prosecutors allege Mr Lynn killed the pair, likely after a confrontation with Mr Hill, while the former pilot has asked the jury to accept they both died in tragic accidents.

At the start of the trial, Mr Lynn's barrister Dermot Dann KC told the jury his client had given an account of Mrs Clay being accidentally shot in the head as the two men wrestled over the gun.

He said Mr Lynn told police after his arrest Mr Hill had come at him with a knife soon after, but fell on the blade and died.

On Thursday, Justice Michael Croucher told the jury of 14 they would be having a long weekend as the next witness, Detective Sergeant Brett Florence, was 'crook'.

'I've got good news and bad news for you depending on how you look at it,' he said.

'The bad news is there are no more witnesses available this week... the good news is you'll be getting a long weekend.

'All that said I will now send you home until Monday at 10.30am.'

Justice Croucher told the jury the case was running 'ahead of schedule'.

The trial continues.