Murder theory 'absurd', lawyer says

The crown case asserting a man was the cold, calculated killer of his lover two decades ago was made up of conjecture and speculation, a judge has been told.

The accused's barrister also described as "absurd" the proposition that his client would meet his so-called intended murder victim in the middle of the day at a railway station with CCTV cameras.

James "Jim" Scott Church, 53, has pleaded not guilty to murdering 23-year-old Leisl Smith, who disappeared from the NSW Central Coast on August 19, 2012.

Her body has never been found but her abandoned car was discovered at Tuggerah railway station more than a month after she vanished.

The Crown alleges Church killed her after she told people she was pregnant to him and because he wanted to save his new relationship with Belinda Lees.

But the defence contends other scenarios could not be ruled out including that Ms Smith's violent ex-boyfriend could have been involved or that she disappeared on purpose.

Continuing his final address in the NSW Supreme Court on Friday, defence barrister Manny Conditsis said the Crown alleged Church was a cold calcuated killer who had planned to murder Ms Smith.

Days before August 19 he allegedly drove to remote locations to find a suitable spot to dispose of the body.

But Mr Conditsis said this was a "spurious hypothesis" revealing nothing more than conjecture and speculation.

It involved "working back to lay the blame of the disappearance of Ms Smith at the feet of the accused".

Church, who was portrayed as having planned to kill Ms Smith and sought to avoid being exposed in some way, had continued to have phone contact with her in the days up to her disappearance, he said.

"The accused, surely to goodness, if he is planning this killing would know if he is talking to Ms Smith on the phone, records would come to light that will reveal it," he said.

"That is not the conduct of a guilty mind."

Church has testified to picking up Ms Smith from Tuggerah railway station at her request, but said he dropped her off at the Old Bakery on the Pacific Highway in Wyong after she asked to get out.

Mr Conditsis submitted it made no sense, if Church was planning to kill Ms Smith, to meet her at a public place in broad daylight where there would be CCTV cameras.

He noted the evidence that the pair had had sex in some bushes on August 13, also suggesting that another private place to meet could be a side street with no CCTV cameras if one was planning a murder.

The judge-alone trial before Justice Elizabeth Fullerton continues.