The last time Wanting Qu spoke with her mother, the call ended on a disappointing note. The platinum-selling Vancouver pop singer was headed to China, but told her mother she was too busy touring to travel to Harbin, where she grew up and learned to play the piano.

"Oh, that's too bad, because I really miss you. I want to see you," her mother, Zhang Mingjie, replied.

Ms. Qu didn't think much of it then, because she had plans for a surprise visit. She didn't know it would be the last time she would hear her mother's voice for years.

Story continues below advertisement

"I remember this so vividly, because it hurts me every time I think about it," said Ms. Qu in her first interview about her mother since Ms. Zhang disappeared Sept. 22, 2014.

That same day, when Ms. Qu arrived in Beijing, her mother did not answer her phone or reply to text messages. After days of anxious calls, a relative told Ms. Qu that Chinese authorities had detained her mother.

Soon after, Ms. Zhang, who built her career by taking on increasingly powerful municipal roles, was formally arrested for abuse of power and stripped of her job titles. Chinese media have accused her of selling state land on the cheap to a company in which her brother held a senior role.

Now, after nearly two years of detention, Ms. Zhang expects to soon face trial for a list of charges expanded to include corruption and taking bribes. The most serious possible sentence is the death penalty.

Ms. Qu is speaking out in part to increase scrutiny on her mother's case. Chinese courts are controlled by the Communist Party and boast a 99.92-per-cent conviction rate.

"I'm worried, but I am keeping my fingers crossed. And I trust that there is still justice out there," said Ms. Qu, who, while still a Chinese citizen, has lived in Canada for 16 years and is dating Vancouver Mayor Gregor Robertson. But she has reason to be anxious.

Ms. Zhang was barred from seeing lawyers for 210 days, and has since complained of sleep deprivation and poor access to medicine.

Story continues below advertisement

"There were a few times she said, 'I can't handle this anymore,'" said Ms. Qu, who wrote a letter to the Chinese consul-general last November begging for better medical treatment after a lawyer reported that Ms. Zhang, a diabetic, had grown swollen and feverish.

By the time her mother sees trial, she will have been in detention for more than 650 days. The trial itself is a subject of uncertainty, initially set for Wednesday but then shifted to a week later. It will be held in a detention centre rather than a courtroom.

"This is a very serious matter, and it's my mother's life on the line here," Ms. Qu said.

Ms. Qu said her mother, born in 1956, was a hard-working, ambitious figure who started working at 16 and rocketed through the administrative hierarchy in Harbin, a petrochemical and agricultural centre 400 kilometres from the Russian border.

She served as a deputy mayor of a city district, and then deputy director of the Harbin Municipal Development and Reform Commission. Ms. Qu thought of her mother as a politician, although it was never something that interested her.

"She was always a workaholic. I sometimes disliked her for that reason," Ms. Qu said.

Story continues below advertisement

Meanwhile, her parents' relationship deteriorated (they are now separated), and home life was tense.

"I grew up not happy," she said.

In 2000, Ms. Qu left for Canada. Her family financially supported her as she cycled through a series of schools before her music career took off.

Chinese functionaries are not well-paid. Even in 2014, the salary baseline for a central government worker at Ms. Zhang's seniority level stood at about $1,400 a month after tax.

Could Ms. Zhang have turned to illicit means partly to fund her daughter in Canada?

Ms. Qu says no, recalling a conversation with her mother about Chinese President Xi Jinping's campaign against corruption. "I'm not doing any of that, don't worry," Ms. Zhang said.

Story continues below advertisement

"My mom – she finds her ways. She borrows money from friends and family to support me," Ms. Qu said. "She makes me know it's hard work making money, and I should not waste it."

But in China, according to a lengthy report in National Business Daily last year, Ms. Zhang was placed in charge of a farm redevelopment as part of a broader state-owned enterprise reform effort. Under her watch, the property changed hands several times, eventually ending up at a company where Ms. Zhang's brother worked as deputy general manager. A former employee of the farm told the newspaper it had been sold off for a small fraction of its value.

Ms. Zhang's case was investigated in part by the feared internal Communist Party graft-busting organization, the paper reported.

Ms. Qu is concerned her mother's arrest is politically motivated. Ms. Zhang has been an active member of the China Democratic League, an officially sanctioned minority political party.

Officials at the court in Harbin did not answer calls from The Globe and Mail; Ms. Zhang's lawyer declined comment, as did Ms. Qu's label, Vancouver's Nettwerk Music Group.

Ms. Qu, who sings in both Mandarin and English, worries that it was her career and the fame she gained in China that brought attention to her mother.

Story continues below advertisement

The singer's strongest sales have been in China, but she has not returned since Ms. Zhang's arrest, fearing for her own safety.

And Ms. Qu is rethinking her long-standing refusal to apply for a Canadian passport. "I just believed in China. I believed that one day it will become like America or Canada – we'll have a passport we Chinese will feel proud of," she said.

"With my mother's situation, it definitely didn't help me with that belief. I kind of doubted."