Pham Phi Ho, 34, lived with his parents at their home in District 6 when the killing occurred, the court heard.
On the night of Aug. 1, 2021, as his mother was sleeping, he suddenly rushed in and stabbed her repeatedly with a knife.
His father jumped in to stop him, but he turned to attack the father, killing him immediately.
His mother managed to run away but he chased after her and kept stabbing her.
His older sister, who was also in the house at that time, got out and called for help.
Police arrested Ho later.
The mother was rushed to a hospital but did not survive.
Ho was then tested positive for narcotic substances.
During their investigation, police determined that before, during, and after committing the crime, he was suffering psychosis due to the use of various drugs, losing the ability to perceive and control his actions.
Ho told the court that he has been using drugs since he was 16.
When the crime took place, HCMC was applying social distancing measures, preventing him from buying drugs and using them on a frequent basis, which had affected his mental health.
Before he committed the crime, he was unstable, so his mother gave him some medicine.
"After taken the medicine given by my mother, I had this hallucination in which someone told me that she had poisoned me and that I must kill her."
Questioned by the court if he is aware of the negative impacts brought by narcotics, he answered: "No."
Representing her parents at the court, Ho's sister cried and asked the jury to lighten the punishment for him.
"We have lost our parents. Now there are only three of us siblings," she said.
Ho also cried at the court.
As a member of the jury board was busy with an emergency, the court was put on hold and will reopen on June 4.