Emotional scenes in court at man's sentencing over Sydney balcony murder

June Oh Seo sits on the balcony after murdering his girlfriend. Photo / Supplied

The father of a young woman murdered by being thrown off a 26-storey balcony has broken down in court saying his family's "hearts are shattered" at losing his daughter.

"My family has lost our whole world," the father of murdered Korean-Australian Hee Kyung "Emily" Choi said, weeping as he addressed his daughter's killer in the NSW Supreme Court today.

"We suffer beyond words, getting through each painful day feeling guilty we couldn't protect our child."

Her body lay in a laneway for 12 hours in October 2017 before Seo was arrested after a stand-off with police after he climbed onto a perspex balcony roof at the top of the block.

The father said the man who bashed, strangled and threw his daughter off a Sydney unit balcony is a "shameless beast with a human face".

Ms Choi, who worked in the finance industry, and June Oh Seo, a painter, began an intimate relationship in March 2017 and travelled to South Korea the next month to meet each other's parents.

"Ms Choi told her friends that the offender was possessive and controlling, including that he did not like her being with male friends or clients, wanted to know where she was, with who and when she would be home," the agreed facts stated.

She later asked him to move out of her apartment, which he did on August 13 but they still stayed in contact.

During the stand-off with police, Seo said: "Hee Kyung is dead and if I get out of here I am going to get a death penalty" and "I am going to spend the rest of my life in jail ... I want to finish myself here".

Turning to murderer Seo, who sat with his head bowed in the dock, Mr Choi said "you have completely destroyed a young individual's life and passion and totally smashed a happy family".

"How can he take someone so cruelly and brutally. Thinking of her ... in heaven breaks our hearts."

Mr Choi said Seo was "devoid of a human face".

Hee Kyung "Emily" Choi. Photo / Supplied

Ms Choi's father did not want his first name divulged. He read out his victim impact statement in Korean before it was translated for Justice Helen Wilson.

Dressed in prison greens, Seo sat in the court never looking up once, as Mr Choi read out his statement in Korean, weeping and his voice choking as he described his "unstoppable, adventurous" daughter.

Mr Choi said his only daughter had worked hard, become a much loved employee in several bank jobs in Sydney and become an Australian citizen.

Seo pleaded guilty last year to the October 9, 2017 murder of Ms Choi whose body was found in a Chatswood lane way after plunging to her death.

The court heard Seo had strangled Ms Choi before she was murdered by falling from the balcony of the apartment.

The killer then spent 12 hours in a stand off with police on a roof ledge.

Ms Choi's father said his daughter had "a dream" from an early age to live and work in Australia.

He said his daughter's birth in 1983 following his son's two years before had "made our family even happier" and as a young girl she had "an unusually independent mind and passion for study".

"By the time, full of passion she went to university she wanted to go to Australia," Mr Choi told the court.

He said his daughter's "unstoppable, adventurous spirit to take on the unknown world" had met a hurdle when "our family was struck by economic hardship and was unable to send her to Australia".

But his daughter "would not give up her dream to study there and ... support herself by working hard".

Mr Choi said his wage as a public servant back in Korea could not pay his daughter's tuition fees, and so she worked part time "never looking to give up her dream".

His daughter kept in contact with her family via video telling them of her plans "to have her own happy family in Australia".

"It really breaks my heart when I remember her shedding tears of joy when she got her job at the Commonwealth Bank," he said.

Ms Choi received letters from customers who were struck by her "kind smile with her customers' best interests in heart".

She obtained permanent Australian residence and then just weeks before her murder, was made an Australian citizen on August 23, 2017.

Mr Choi broke down in court again, sobbing, as he recalled his daughter showing her family a photograph of her accepting her citizenship certificate.

"A short time later our family happiness was shattered by the devastating news about our daughter," Mr Choi said.

"Our hearts are broken because she has done her best to achieve her dreams and life was taken away from our poor daughter."

He said his wife had pleaded with Seo "many times" to support her daughter.

"How can he take someone away so cruelly and brutally just because he wasn't able to have his own way?"

Mr Choi said his son had quit his job since the murder and was unable to tell his own children, who still begged to speak to their aunt on the phone.

He said Seo had showed no remorse for the murder and had initially told police Ms Choi "had committed suicide by jumping from the verandah of her own apartment".

"He even had the temerity to apply for bail," Mr Choi said.

"How could he [have] killed her so brutally ... devoid of a human face.

"On December 7, 2018, a year and two months later, he confessed to his crime, only to have his sentence reduced.

"Our family [hopes] your honour will deliver a wise judgment."

Justice Wilson will pass sentence this afternoon.