Lynn, 57, is on trial charged with two counts of murder over the deaths of campers Russell Hill and Carol Clay in Victoria's alpine region in March 2020.

The airline pilot told police, and the jury, the deaths were accidental.

The accused double murderer's legal team closed their case before a jury of 14 at the Supreme Court in Melbourne on Wednesday, about five weeks into Lynn's trial.

He claims Mrs Clay was shot in the head after a struggle between the two men as he tried to get his shotgun back from Mr Hill, who he said took it from Lynn's car.

Mr Hill died during a second struggle over a knife, when Lynn claims he was trying to defend himself.

Prosecutor Daniel Porceddu on Tuesday said Lynn's entire story was a "fanciful" work of fiction and he had one year and eight months to concoct a script about what had happened, before he was arrested.

But Mr Dann attacked gaps in the prosecution's case, labelling it as "desperate" and accusing prosecutors of breaking court rules by failing to put their theories to Lynn during cross-examination.

"They say it's fanciful and fiction - that's propaganda, false, unrealistic," the defence barrister said on Wednesday.

"(The rule) been in existence for 130 years, they just turned their back on it. 

"The rule - based in fairness, humanity, decency - was totally obliterated."

Lynn, who admits burning the crime scene and then hiding and destroying the bodies of the two campers, offered to plead guilty to destruction of evidence before the trial began.

He also admits failing to properly store his two guns, leading to Mr Hill taking a shotgun and ammunition from Lynn's car.

Mr Dann said a gun storage charge would have cost the Jetstar pilot his career, as he asked jurors what they would do in that situation.

"He's left the gun in the car, the magazine in the car, it's unsecured and he's failed in his storage of the gun," he said.

"You've got to put yourself in Mr Lynn's shoes, presuming of course that he's innocent.

"This was a disaster ... of course he's thinking about himself, of course he's selfish, of course he was callous."

Lynn's story was shown to the court in a police interview after he was arrested in November 2021.

He took to the witness stand last week, where he again stuck to his version of events.

"It's called the longest and loneliest walk in the law, you expose yourself," Mr Dann said.

"He came through that process totally unscathed.

"There was confidence, there was composure about him ... it comes from a presumption of innocence - he knows what he's talking about, he's lived through it."

Mr Dann said the prosecution's case had no factual foundation and failed to "fundamentally demonstrate if Mr Lynn is guilty".

"You're being asked to find a man guilty of murder, there's on the prosecution case zero factual foundation, zero motive, just a complete blank. Does that sit well with any of you?

"He thought he was going to be wrongly blamed and he is being wrongly blamed."

Lynn's wife Melanie and son Geordie sat in front of him and behind his lawyers in court on Wednesday, holding hands and nodding along in full view of the jury.

Justice Michael Croucher will outline the charge to the jury on Thursday, before sending them away to deliberate on a verdict.