"There was a looming threat if the deceased ever left him she would or might be killed," crown prosector David Scully said on Friday.

He was making submissions in the NSW Supreme Court at the sentence hearing of Jason Lloyd.

The 41-year-old has pleaded guilty to murdering his on-off partner Lynda Greenwood, 39, in October 2020 outside her unit at Como.

Neighbours found the critically injured woman in the early hours in the building's driveway.

Lloyd had attacked her with a baseball bat and repeatedly stabbed her.

In submitting there had been a degree of planning, Mr Scully said Lloyd purchased the bat two weeks earlier and, on the night of her death, went to her house with two weapons.

Referring to the knife, he said: "The suggestion he found it in a toilet is inherently implausible".

At the time he was the subject of an apprehended violence order and in the months before had sent texts threatening to kill her if she left him.

They included saying "if I can't have you no one else can", "I will snap you in half" and referring to having "a nice sharp knife".

Lloyd was putting her in what must have been unimaginable fear, Mr Scully said.

He submitted that when Lloyd bought the baseball bat he was contemplating using it against Ms Greenwood and or against any other man she may be seeing.

But defence barrister Tony Evers said there may have been other reasons for buying the bat such as for a present or to use to play with.

"If he is contemplating to kill her, a baseball bat is a strange type of weapon," he said.

As well as the AVO, Mr Scully stressed Lloyd's criminal history which included a threat against a previous partner involving him running his finger across his throat.

Lloyd drank at four hotels before going to Ms Greenwood's home.

Mr Scully said Lloyd knew there was a link between alcohol and his violent behaviour, with the evidence including his texts.

In one he said he was not violent, "it's only the drink".

Mr Evers said Lloyd had made genuine steps to address his drinking problem before the killing.

He also noted there was no evidence about how much alcohol he consumed at the four hotels and if it played any role in his offending.

Referring to the Crown's submissions about planning the attack, Mr Evers said he may have had the bat contemplating violence to an unknown male with Ms Greenwood.

He previously made threats of serious violence, which he did not carry out, and they could have been expressions of anger.

Submitting the murder was not "a carefully planned enterprise", he noted CCTV cameras would have been in the hotels and the train.

Indeed, there would have been one in the taxi he caught away from the scene.

Justice Geoffrey Bellew will sentence him on July 15.

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Australian Associated Press