Charlotte Wood says she is still haunted by the murder of her roommate, model Diana O'Brien, in Shanghai in July. (Courtesy of Charlotte Wood)

The roommate of a Salt Spring Island model who was murdered in Shanghai, China, says the experience still keeps her awake at night.

Charlotte Wood, 21, was the first to find the body of Diana O'Brien in their building's stairwell on July 6.

Earlier that Sunday evening, O'Brien had returned from a modelling job to the apartment the two shared.

The two had a bite to eat together, and then Wood went out with friends while O'Brien stayed home to rest.

Hours later, Wood came home to find a woman's stabbed body in their apartment stairwell. She immediately ran upstairs to get O'Brien.

"I didn't make it in. I just saw stuff happened in my apartment," Wood told CBC News on Monday in an exclusive interview at her mother's home in Metchosin, a suburb of Victoria on southern Vancouver Island.

Diana O'Brien, 22, of Salt Spring Island, B.C., was found dead in her apartment building in Shanghai on July 6. (CBC)

The furniture in the apartment was overturned, and there was blood on the floor. It was O'Brien who had been killed.

Wood was questioned for hours by Chinese police. When they let her back into the apartment a week later, it was still a grisly crime scene.

"I tried not to look at Diana's room because it was the worst," Wood said. "I went in there. It was a blur. I just grabbed my things … It was too emotional being in there. It wasn't the same apartment."

Less than a week later, police arrested Chen Jun, 18, who had recently been working in a nearby coffee shop, and charged him with murder.

He allegedly confessed to entering O'Brien's apartment to rob her, saying he stabbed her when she tried to hit him and run away.

Critics have suggested the swift arrest and the man's inconsistent confession make his arrest look more like a public relations move before the Beijing Olympics rather than real police work, but Wood disagrees.

"They showed me tapes of the guy entering the building, riding his bike around, leaving with my stuff," she said. "They found all my stuff with him. So, I don't know. I don't know how they could have planted something on a random guy."

Modelling agency shut down

Victoria's Barbara Coultish modelling agency contracted Wood and O'Brien to JH Models in Shanghai, a new, small agency, which immediately shut down after the slaying.

O'Brien, left, and Wood, second from left, enjoy a meal with some friends in Shanghai. (Courtesy of Charlotte Wood)

The agency only had three models at the time of the killing: Wood, O'Brien, and a man. Wood said the agency asked her and O'Brien to do some strange jobs like dancing on stage to promote a new brand of liquor.

"We both didn't want to do it," Wood said. "We did it twice. We were both like, 'We don't want to do this anymore'."

O'Brien was disappointed with the work and missed her boyfriend and wanted to return home, Wood said.

After the killing and the investigation, Wood stayed and picked up work with another agency.

But now that Wood herself has returned home to British Columbia, she says she is still struggling with the reality it could have been her home alone in the apartment that night. The unthinkable tragedy is only starting to hit home now, she said.

"It's just hard," Wood said. "It's just weird being home and finally dealing with everything."

With files from Heather Robinson