Legislator Tsai Cheng-yuan (蔡正元) explained his “urgent proposal” in a brief post to Facebook in the morning entitled “Die, random killers!”

The post calls for a mandatory sentence of life in prison or the death penalty for acts of indiscriminate killing, while a proven criminal attempt to commit random mass killings would bring a maximum sentence of three years.

The mandatory sentence under Tsai's proposal would be death for indiscriminate killings perpetrated on a metro system, railway, high-speed railway, cable car, or any other land, water or air transport. An attempt to commit those killings would carry a maximum sentence of five years.

Tsai said separately that same day that there is a need to separate random killings from targeted killings. Since public transport constitutes a closed space, random acts of murder could cause enormous numbers of casualties, he said, arguing that imposing a mandatory death sentence would deter anyone from committing copycat crimes.

He said that he is working on another draft amendment to the Mass Rapid Transit Act that would implement a maximum sentence of five years for anyone carrying guns, ammunition, knives, or other lethal weapons on public transport. Anyone found guilty of “illegally harassing” passengers would be subject to a maximum of three years behind bars.

Tsai said he is soliciting signatures from legislators to endorse the proposals.

He initiated the proposal amid renewed calls by civic groups to scrap capital punishment following the executions of five death-row inmates last month, Taiwan's first executions in a year.

Lin Hsin-yi, executive director of the Taiwan Alliance to End the Death Penalty, gave a low-key response to Wednesday's tragedy.

She said that the most important thing at present is for the public to think about how to help the victims of the metro slashing spree and ease the survivors and their relatives out of the suffering brought about by the tragedy.

The unprecedented Wednesday killing shook the nation after a 21-year-old student allegedly killed four people and injured over 20 in a random knife attack on a Taipei Metro train running on the Bannan (blue) line.

On Thursday morning, the New Taipei District Court agreed to allow prosecutors to put Cheng Chieh, the sole suspect, into custody after a hearing that lasted only 10 minutes.