It was September 29, 2015, when Cang Sun received a phone call from his son's kidnapper.

Sun was in the process of wire transferring another instalment of the ransom for his son, Peng Sun, toward the $2.5 million demanded by the kidnapper when his phone rang.

He had already paid more than $300,000 and asked to hear his son's voice.

"The kidnapper said, 'OK,' and in less than one minute, he brought Peng to the phone, there was a voice that said, 'Dad, dad, help me, please give them the money,'" Sun said through a translator.

"I heard the voice and I know it wasn't my son."

According to Sun, who owns a construction company in Beijing, the kidnapper insisted it was Peng Sun, but accused Sun of trying to use a secret signal when he asked to hear his son say his sister's birthday.

"The kidnapper said, 'If you don't give the money, I'll kill your son right now,' and he hung up the phone," said Sun.

The kidnapper phoned back a minute or two later and began counting down from 10, saying he would kill Peng Sun, and hung up when he had finished.

"At that time, I realized my son had already been killed because that wasn't the voice of Peng," said Sun.

Gruesome discovery

Peng Sun's body was discovered after police in North Vancouver swarmed a residential street in Lynn Valley early in the morning of Sept. 29, 2015.

A black BMW, a white Bentley and a Chevy Malibu, were towed from the scene of a fatal shooting in North Vancouver in Sept. 2015. (Kirk Williams/CBC)

Four men were arrested and charged, but two eventually had their charges stayed.

Tian Yi Zhang was charged with first-degree murder, kidnapping and indignity to a body, but pleaded guilty to manslaughter, unlawful confinement and extortion on Feb. 9. His sentencing hearing is expected to begin on Tuesday in B.C. Supreme Court in Vancouver.

Casey James Hiscoe pleaded guilty to conspiracy to unlawfully confine and accessory after the fact to murder. He has yet to be sentenced.

'My life is ruined'

But for Peng Sun's parents, who say they had been assured by Canadian authorities that their son's killer would face first-degree murder charges, the manslaughter plea isn't enough.

Hua Li clutches a tissue as she describes her son, Peng Sun. Li asked that her face not be shown, due to concerns for her personal safety, following the kidnapping and killing of her son. (Rafferty Baker/CBC)

Along with other family members, they flew to Vancouver for the sentencing.

"We want to have the killer to be punished fairly and we want justice," said Sun, before the punishment had been handed down by the court.

"If that's the law of Canada, it's unfair. For the killer, it's not a fair punishment," he said.

Peng Sun's mother, Hua Li, wept when she spoke of her son.

"He was very sunny, bright, and all his friends are like him — popular," Li said through a translator.

"My life is ruined," she said. "That's the only son I had, and I'll never get another one."

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