Why is chalk evidence?

Chinatown Detective 2 Chalk is evidence, because the fingerprints on the chalk are different from those of the left and right hands.

At the end of the film, Liu Haoran actually said to "five million" with a bag of chalk, this is the evidence: the murderer is left-handed, the fingerprints on your chalk are left-handed, and you are left-handed, so the murderer is you.

Sean's next sentence should be: I beg you to give the chalk to the police just to buy me some time to dispose of the body.

Yi Song threw a chalk foreshadowing.

"Detective Chinatown 2" Yi Song smashed a piece of chalk, which was a hint to Qin Feng and an approval to his opponent. In the first detective chinatown, Si Nuo's gloomy smile is like chalk thrown away. Yi Song killed Liu Guofu for his sister, and then framed the doctor, making the police and everyone think that the doctor killed him. Yi Song escaped safely, and finally the chalk scene actually paved the way for the third one.