Adam Margolis, 41, was sentenced in the Supreme Court on Tuesday after a jury earlier this year found him guilty of Mai-Yia Vang's murder. He will be eligible for parole in 17 years.

Margolis strangled Ms Vang at a Butler Street property sometime on February 24 or February 25, 2018.

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Justice Christopher Beale described Ms Vang's death as "violent and untimely".

"She was only 26 years of age," the judge said. "No sentence that I can impose can right the wrong you have done to Ms Vang and her family."

Margolis and Ms Vang formed a relationship in January 2018 after they met through an online chat service.

Ms Vang then moved in with Margolis at his California Gully home on February 18 that year.

In the week leading up to Ms Vang's death, the court heard the couple had arguments about Ms Vang's apparent contact with an ex-partner.

After a "heated argument" late on February 24 or in the early hours of February 25, Margolis choked or strangled Ms Vang until she died.

The court heard in the proceeding 24 hours, Margolis used Ms Vang's phone purporting to be her.

He sent several messages in Ms Vang's sisters' group chat, telling them she was feeling sick and she needed to sleep.

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Margolis then made plans to kill himself and wrote a 12-page email explaining why he killed Ms Vang.

Margolis said Ms Vang had "overtly assaulted (him) so many times" and that he "lost control".

He wrote that he "blacked out" during the argument and regained consciousness to see Ms Vang in a choke-hold.

In the email, Margolis said he told Ms Vang he was sorry during the murder and that he "tried to minimise (her) suffering".

Margolis sent the email to three associates, one of whom received the email several hours later and contacted police.

Police arrived at Margolis' address in the early hours of February 27 to find Margolis lying on a mattress in his bedroom.

The court heard he appeared to be having a drug overdose. Police asked him if there was anyone else in the property and he indicated to another bedroom.

Officers entered the room and found Ms Vang's body. She was lying face down with her torso on the bed and legs on the floor.

An autopsy report said there was male DNA on Ms Vang's neck and under her fingernails, which was likely to have come from Margolis.

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Justice Beale said the circumstances around the Ms Vang's murder were aggravating features.

The judge said while Margolis told the jury the email was a "false confession", Margolis' allegations that Ms Vang assaulted and "deliberately triggered" him were "not accepted as fact".

Justice Beale said Margolis continued to pursue Ms Vang around the California Gully property, despite her being physically smaller than him.

The judge also noted the murder was committed in a family violence context, Margolis purported to be Ms Vang after her death, and he left her body on the floor for several hours after the murder.

But Justice Beale told the court he needed to take into consideration Margolis' diagnosis of borderline personality disorder and long-term post-traumatic stress disorder.

"It is likely that the substantial prison term which I must impose on you will exacerbate your mental health issues and make jail harder for you than for prisoners who do not have such issues," the judge said.

Justice Beale noted that while Margolis' had no relevant prior convictions, his prospects of rehabilitation were "guarded".

"Your mental health problems seem entrenched," the judge said. "I find that there is a significant risk that if you struck up another intimate relationship which turned sour, you could again lose control and act violently.

"Protection of the community must inform the sentence I impose."

Margolis was sentenced to 23 years in jail, with a non-parole period of 17 years. His 1202 days of pre-sentence detention were reckoned as already served.

During his plea hearing last month, Margolis indicated he would appeal his conviction and sentence.

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