Tokyo, Japan - A 24-year-old man dressed in a Joker costume who injured 17 people in a knife and fire attack on a Tokyo train line had wanted to "kill people and get the death penalty," police said on Monday, according to Japanese media.

On Halloween night, the man wearing an outfit resembling the Batman villain had attacked passengers with a knife in a Keio line train and also set fires using lighter fluid.

One elderly man who was stabbed in the chest was reported to be in serious condition.

Pictures and videos taken by witnesses showed a man wearing a purple suit with a green shirt. Japanese media reported that the attacker told police he was a big fan of the Batman franchise.

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He was arrested while still at the scene on suspicion of attempted murder.

Police said he had been pondering how to receive the death penalty for months, local media reported.

He was said to have deliberately chosen an express train for his violent crime spree because such trains stop less often and are usually crowded with passengers.

The man also told investigators that he regretted not being able to kill anyone in his attack.

Two hours before the incident, the perpetrator was reportedly in Tokyo's trendy Shibuya district, where people were partying in Halloween costumes.