The wheelchair-bound accused man is on trial in the Supreme Court after he allegedly shot his ex-partner's new male lover in the garage of the former family home at Littlehampton, in the Adelaide Hills, in October 2017.

The court has heard the alleged victim, 26, retaliated by attacking the accused man with an axe, rendering him paralysed from the neck down.

But in her closing remarks to the jury on Wednesday, defence counsel Marie Shaw said the victim's account was undermined by forensic evidence in the case.

"He is not telling you the truth about where he was shot. He's not telling you the truth about how he was shot," she told jurors.

Ms Shaw said the injuries on the accused man's neck could not have been inflicted from a lying down position, as the victim told the jury during his evidence.

"He has to be covering up that this is not self-defence when he strikes my client repeatedly in the neck," she said.

"He must have been standing over my client to ram that axe into my client's neck eight times in a very localised area. He's not swinging randomly. He's not lying on the floor beside him."

Previously, jurors heard the accused man was "not happy" when the woman told him she wanted to separate in June 2017, but Ms Shaw said her client had no motive for the alleged attack.

"He's in employment, he's supporting himself ... and he is wanting to have a greater stake in his children's lives," she said on Wednesday.

"He has plans for the future."

Ms Shaw said her client's ex-partner had taken issue with a proposed 50-50 custody arrangement of their children.

"There's her obsession with the matrimonial assets and that she grasped the entirety of them, there's the life insurance money that will fall into her hand if my client's deceased and it all depends very much on what happens with custody," she said.

The court has also heard the ex-partner met another woman on an app after the shooting incident and the pair lived together for a short time at the Littlehampton home.

The ex-partner denied they were ever in a relationship and that they discussed suffocating the tetraplegic man, though Ms Shaw told the court the other woman was spotted outside the accused man's rehabilitation centre on New Year's Day 2018.

No one involved in the case can be named due to suppression orders imposed by the court.

After more than four weeks of evidence and submissions, the jury is expected to begin deliberations on Friday.

Australian Associated Press