An exchange student from China killed in front of her own webcam while her helpless boyfriend looked on was being stalked by a spurned lover, according to friends.
Canadian officers found the semi-naked body of Qian Liu in her Toronto apartment after receiving a tip-off from her boyfriend who had been chatting with her online 6,600 miles away in China at the time of the attack.
A police manhunt is continuing for a person seen on her boyfriend's webcam struggling with the "hardworking" 23-year-old student before she died.
But the mystery over what killed Miss Liu deepened today after a police autopsy failed to show a cause of death, intensifying speculation she may have been given some form of "lethal injection."
Detectives had revealed Miss Liu was "unclothed from the waist down" but that there was no trauma to the body or signs of sexual abuse.
Although police are unwilling to comment on reports that Miss Liu was given some form of injection they have admitted toxicology tests continue to be carried out.
Miss Liu's boyfriend said he was talking to the English Language Institute student at about 1 am Friday morning when there was a knock at the door.
"She opened the door to a male. She could have known the male but he was unknown to the online witness," Toronto Police Det–Sgt Frank Skubic said.
Speaking from Beijing, the witness then told police he watched through the webcam lens as the muscular man with medium-length brown hair asked the victim to use her mobile phone.
He then watched as a violent struggle developed between Liu and the man, although some of the fight also took place out of the camera's range.
The suspect -- described as white, in his 20s, 6ft tall and about 200lbs -- then turned off the IBM ThinkPad T400 laptop, which is now missing.
The victim's stunned boyfriend quickly used social media to contact others who knew the woman in Toronto and China but police didn't arrive at her apartment until around 10 hours later.
"The online witness became concerned and contacted several people known to the deceased here in Canada, and appealed to them to go and track down her welfare," Det–Sgt Skubic added.
"It was as a result of somebody responding to that plea by the online witness that she was discovered."
Miss Liu was one of eight people who lived in the multi-unit house and had only moved in January of this year.
One of the woman's friends said the man who entered her room had been pursuing her romantically.
"The suspect once shared the same house with Liu’, the friend said.
"He was chasing after her, but she refused, then he started stalking her by texting her all the time," the man, who was interviewed by police for 12 hours, wrote in an online chatroom.
The same friend said he was on the scene when the landlord opened the door Friday morning, finding Liu's body on the floor with one arm extended toward the door.
"It felt like the sky had collapsed," he wrote. "I called 911 but I couldn't spit out one single word."
In what is Canada's first murder witnessed on the Internet police have issued an urgent appeal for computer experts to help recover images of the killing at York University Village.
Officers said the attack "wasn't being recorded by any third-party software" but they believe the missing computer could still reveal the student's final moments.