Prisoners remained something of a grey area.
In 2003, city authorities said 15 Vietnamese inmates were eligible to stay in Hong Kong on completion of their sentence, while 18 others would be deported.
Vo, who now speaks Cantonese better than Vietnamese, was never told what his status was.
So when he walked out of prison in 2016, he expected to be a free man.
He got as far as the prison gate.
“A number of immigration officers waiting there handcuffed me and told me I would be taken to the detention center,” he recalled.
Two years ago he won a judicial review against the immigration department’s initial decision to deport him.
A second immigration hearing is imminent but has been delayed by court closures during the coronavirus outbreak.
Hong Kong’s government declined to comment on Vo’s case.
The Security Bureau said there are currently 18 Vietnamese nationals who have been deemed ineligible for local resettlement for various reasons including imprisonment.
Vo argues he might be subject to political persecution if he was repatriated because his biological father was a South Vietnamese soldier who fled overseas and left him in the care of the adoptive parents who then sent him alone to Hong Kong.
He also fears being prosecuted a second time for the murder in the refugee camp.
Asked about that killing he replied: “I certainly regret it. I did not know how to behave properly. [Violence was] my only way to protect myself and others.”