A man has been arrested after a woman suffered an hour of sexual assaults and then fell to her death from a Sydney balcony, police say.
Four young Asian students endured horrendous sexual assaults lasting up to an hour at the hands of a knife-wielding predator before two fell from a Sydney balcony, one to her death.
Chinese student (Elva) Liao Wei, 18, died after falling from her third-floor Waterloo unit about 1.40pm (AEDT) on Sunday.
Her boyfriend, Korean Tae Wook "Chris" Han, 19, remains in hospital with serious spinal injuries from which police say he may never recover.
A 26-year-old man was arrested in Castlereagh Lane, Redfern, about 8.20pm (AEDT) today, police said.
The arrest comes after detectives today released CCTV footage of a man wanted over the home invasion and assaults, as a large squad of police work on the murder investigation.
"The man was conveyed to Redfern police station where he is currently assisting police with inquiries into the incident," a police statement read.
"This is a particularity horrendous crime. It's shocking," Detective Superintendent Geoff Beresford told reporters in Sydney today.
"The fear that those people must have felt during this attack would be indescribable."
At the time, he said investigators were considering a range of possible scenarios for what occurred and had not ruled out the intruder may have been drug-affected.
The attacker followed one of his victims into the security apartment complex before holding a knife to her throat and forcing her to let him into the unit, police said.
Mr Han and Ms Wei were held in the apartment, along with two Asian women aged 19 and 20.
"We can confirm that there were a number of sexual assaults on all of the victims," Supt Beresford said earlier today.
"In relation to the deceased person and obviously the male person who suffered injuries from the fall, we do expect that they were forced either by fear or by other means (to perform sex acts)."
He said it was not yet known whether the pair was forced off the balcony or were trying to escape.
Peter Price, head of the Waterloo Study Centre where the couple were students, said Mr Han had broken his back, pelvis and femur, as well as ankles and wrists.
"He's black and blue with bruises and is half-sedated as well, given the extent of his injuries," Mr Price told AAP.
Wearing a neck brace, Mr Han was chatty at times with friends keeping vigil by his hospital bed, he said.
Ms Wei's family had secured passports and were expected to arrive in Sydney in the next couple of days, Mr Price said.
