It was already too late when Jamie Lee Dolheguy uttered those words to police in July 2018, confessing to strangling a man she met online.

Maulin Rathod, a 24-year-old international student in Melbourne from India, had exchanged a series of messages with the teen before meeting her on the day of his death.

Dolheguy, now 21, was jailed on Thursday for nine years, but could be out in as little as three years and three months.

In Dolheguy's Plenty of Fish profile she revealed she was dating for the first time, had borderline personality disorder, suicidal ideation and extreme fetishes including bondage.

"We'll do whatever you want," Mr Rathod told her.

But while he drove to her house, believing they would sleep together, Dolheguy went online and searched "I'm going to kill someone tonight for fun".

Dressed up as the character Lolita, the then 18-year-old discussed choke play with Mr Rathod before wrapping a sex toy cable around his neck and strangling him.

"It'll be OK, it'll be over," she whispered to him.

Dolheguy has a history of violence, and held beliefs she was a werewolf.

While being held in a maximum security prison wing, Dolheguy threatened to kill another inmate, threatened to harm a child in front of its mother and attempted to take her own life 25 times.

After killing Mr Rathod, Dolheguy immediately phoned police and confessed, telling them he didn't seem scared.

Supreme Court Justice Peter Almond disagreed.

"One can only imagine the terror he felt when he realised that despite his urgent tapping, you were not going to let go," he said.

It was never in question that Dolheguy had killed Mr Rathod, but her lawyers had argued she didn't intend to murder him, despite prosecutors arguing it was plain even before he arrived what she had planned.

Her barrister Sharon Lacy said Dolheguy was so damaged, her mind in such chaos, no jury could be satisfied of her murderous intent.

A jury convicted her of manslaughter last December.

Back then Justice Almond was unable to take into account her severe personality disorder as a mental impairment.

Victoria's Court of Appeal only overturned its position on the disabling effects of a personality disorder in August, opening up new sentencing options in her case.

Dolheguy suffered extreme abuse as a child and was taken into care at 10.

She has a history of self harm and suicide attempts and from the age of 14 lived with full-time carers. Those provisions were taken away when she was 18 and she lived alone.

"Because of her dreadful upbringing, she never developed a sense of basic trust in the world around her," forensic psychiatrist Andrew Carroll said of her.

Justice Almond ordered she serve a minimum of five years and six months. She has already served two years and three months.

Australian Associated Press