A HOMELESS man who subjected four international students to a "reign of sexual terror" in a Sydney apartment has been sentenced to 28 years in jail.

Brendan David Dennison held the four students hostage at knife-point for more than an hour in October 2008 as he ordered two of them to perform degrading sex acts on himself and each other, The Daily Telegraph reports.

His depraved rampage led to the death of a 19-year-old woman, who fell naked from her sixth-floor balcony of the Waterloo apartment along with her 19-year-old boyfriend in a desperate bid to escape.

Dennison's sentencing in the Supreme Court heard he was on a drug binge and had no memory of the sickening attack, despite pleading guilty to 19 charges including the young woman's murder and recklessly inflicting grievous bodily harm to her boyfriend.

The court heard Dennison, who was released from prison just four months prior, had been injecting the drug ice "most days" for a week and hadn't slept leading up to the crime.

The facts of the case state Dennison was "wandering homelessly and aimlessly" when he followed a friend of the couple's into their building and held a knife to her throat in a lift.

She handed him $50, but that wasn't enough for Dennison, who directed her out of the lift and into the open door of her friend's unit.

He took a large knife from the kitchen, forced the man to strip naked and then cut the women's underwear off them before subjecting the four to what Justice Elizabeth Fullerton described as "a reign of sexual terror."

The traumatised students tried to appease Dennison by offering him money, but he continued to force them into sex acts and repeatedly raped one of the young women until she fled to the balcony, climbed over the wall and tried to swing herself to the level below.

Hearing her cries for help, her boyfriend followed, but she fell 12.5m to the concrete below before he could reach her.

In attempting to swing his own body to the balcony below, the young man also fell as horrified neighbours looked on.

Before Dennison left the unit, the other two women barricaded themselves in a bedroom and called police.

The court heard Dennison had no history of sexual offences and his excessive use of the drug ice probably contributed to his behaviour, but Justice Fullerton said that was not a mitigating factor.

In a letter to the judge, Dennison said he "doesn't remember anything that happened that day and doesn't want to" because he is horrified by what his lawyers have told him.

He also "expressed sincere remorse for the horror of his actions" in the letter and apologised to the families and friends of his victims.

But the court heard Dennison earlier told police, "It wasn't meant to go like that. It got out of control."

He also told them he wasn't responsible for the young woman's death.

"I didn't kill her, they're saying she jumped. That's not my fault," he said.

Justice Fullerton said he was liable for murder because the young woman died while trying to escape from his "detention."

"Her attempts to escape...were a natural consequence of his conduct," she said.

Dennison was sentenced to a maximum jail term of 28 years, with at least 21 years behind bars.

With time already served, he will be eligible for release in October 2029.

Originally published as Rape monster jailed over teen's murder