That meant Li Tim-chuen broke the law again just 1 1/2 years after he was paroled for murdering a female colleague in 2000 when he worked for the Food and Environment Hygiene Department.

Li had earlier pleaded guilty to two counts of throwing corrosive fluid with intent to do grievous bodily harm in an attack on four employees in the care center where he lived.

The attack was driven out of revenge after the home failed to return Li's deposit, the court heard.

During the sentencing, Justice Andrew Chan Hing-wai slammed Li's actions of causing permanent injuries to innocent people as "heinous."

Li had also been fined for assault in 1969.

Li had lived at Pak Ho Gerocomy Center between June 2018 to August 2019 after he was paroled in 2018. But he failed to notify the care home in advance when moving out, and the home had withheld his deposit of HK$8,200.

Failing to get his deposit refunded after repeated requests, Li took several bottles of drain cleaner to the reception counter of the care home at around noon on January 25, 2020, and splashed the liquid on four employees who were dining there. The four suffered serious burns, while one was diagnosed with post-traumatic stress disorder after the incident.

During yesterday's hearing Li screamed that he was "defrauded" by the care home, which led the judge to adjourn for 10 minutes so Li could calm down.

But Li continued shouting when the court resumed, and the judge warned he would be taken to a detention room if it went on.

Li's lawyer said leniency could be shown given his age, but Chan pointed out Li had planned to cause severe harm to others by taking three bottles of drain cleaner with a 98-percent concentration.

Chan further said Li is "as dangerous as 22 years ago," adding that he should not be paroled until he could no longer threaten the community.

The judge started Li's prison term at 20 years for the two counts after considering his criminal record. The prison time was reduced by one-fourth as Li pleaded guilty on the first day of the hearing.