Pedestrians cross a street at Taipei's bustling Kuanghwa Market district Reuters

A Taiwanese man, who unleashed a brutal knife attack on a four-year-old girl on a busy street in the capital, Taipei, was handed life imprisonment by a district court on Friday (12 May).

Wang Ching-yu, 34, pleaded guilty to killing Liu Yi Jie as she was on her way to the train station with her mother to meet her grandfather and younger siblings in March 2016. Wang decapitated the girl, fondly referred to as 'little light bulb', with a kitchen knife – despite her mother's frantic attempts to fend him off.

Passers-by tried to stop Wang, but it was too late as he had already fatally wounded the girl. The crime sent shockwaves throughout the island and led to hundreds of people calling for Wang to be executed.

Prosecutors demanded the death penalty for what they described as an "extremely cold-blooded" crime but Wang was spared execution as judge Tsai Shou-hsun told the court that the defendant had a "mental handicap".

According to the ruling, Wang was found to be schizophrenic and therefore could not be sentenced to death. However, prosecutors argued that Wang should be killed after a psychiatric report deemed him to have been mentally sound enough to be responsible for his actions, Agence France-Presse (AFP) reported.

As the defendant listened to the verdict, he replied: "I understand."

The victim's family were not in court.

During proceedings, Wang told the court that he had hallucinated he was a Chinese emperor from Sichuan province and that killing the girl would bring him concubines to "carry on his family line", according to reports.

He confessed that he knew the murder was wrong because no such woman had given him children.

Wang had previously been arrested for drug-related offences, but was not under the influence of narcotics when he carried out the murder.

Taiwan resumed the death penalty in 2010 after a five-year moratorium. A majority of the island's people support capital punishment.