TAIPEI, July 21 -- A 21-year-old college student was charged on Monday with multiple counts of murder and attempted murder for a knife attack on a subway train in May, according to the New Taipei prosecutors office.

Cheng Chieh, who is accused of stabbing passengers randomly on a moving train on May 21, has been charged with four counts of murder and 22 counts of attempted murder.

Prosecutors asked the court to give Cheng the death penalty for the crimes, which were described as "mass killings" that were "heinous and without humanity".

Cheng underwent a psychiatric assessment at Taiwan University Hospital. He was found to be "normal" after four face-to-face interviews and a body examination. This was essential for the prosecutors to ask for the death penalty.