A cleaning woman followed a trail of blood from Diana Gabrielle O'Brien's apartment door to find the Canadian model's lifeless body.

O'Brien, a 22-year-old from Salt Spring Island, B.C., was found dead in the staircase of a Shanghai building on Monday.

"There was blood everywhere, dripping from her apartment door all the way down one flight of stairs," Xiaoli Ouyang told CTV News.

When Xiaoli found O'Brien's body, the model was wearing "house clothes," suggesting she may have been attacked in her apartment.

A nearby parking attendant said the model was allegedly stabbed multiple times, but that has not been confirmed by Chinese police. A homicide investigation is underway.

In the past few days, police had said little about her death; they had not even acknowledged it was a homicide. On Wednesday, they released new details about the incident, telling reporters they were called to her apartment by a domestic cleaner.

Police have now set up a massive investigation centre on the main floor of O'Brien's apartment building, according to CTV's Steve Chao, reporting from Shanghai.

"We walked into this command post and in one room we saw at least a dozen investigators looking through security camera footage," he said.

"There is no question people are looking at this as a homicide and are looking at this case very seriously."

One of O'Brien's roommates, 21-year-old Charlotte Wood, reportedly identified the body. Police have asked her to stay in Shanghai, in case she can help in their investigation.

Wood is a model from Victoria, B.C., and had worked for China's JH Model Agency -- the same agency that had signed O'Brien for a three-month contract. When CTV visited the company's office earlier this week, an employee said he had never heard of O'Brien. There are reports that the agency has since shut its doors.

O'Brien had shortened her contract to one month. Her boyfriend, Joel Berry, said she had been homesick.

"She was missing home a lot ... and we all wanted her home too," said Berry, who spoke to O'Brien the day before she died. "It's just a huge loss. I find it hard to believe I'll ever meet anyone like her ever again."

He also said she was not concerned about the safety of her job.

"She was living her dream. It was just a tragic, tragic loss," he said.

Chao said Chinese officials and residents are concerned about what impact news of O'Brien's death may have on next month's Olympics.

"Many people in the neighborhood stressed to us to tell Canadians (China is) still very safe and crimes like this are very rare," Chao said.

With a report by CTV's Steve Chao in Shanghai