Lu Chuan picked up the murder weapon and observed carefully: "The fingerprint patterns on this weapon are blurry, with severely spread edges. It seems to be a kind of blurred impression formed after the original fingerprints peeled off."
There are many ways to make fingerprints disappear. Some methods make fingerprints disappear for a short time, while others can make them disappear for a long time.
Whichever method is used, it is sufficient for committing a crime.
Regarding the fingerprints on the murder weapon, Lu Chuan leans towards a theory that they were created after soaking in diluted nitric acid, causing the fingerprints to peel off.
The person must have had some research on fingerprints, at least knowing what concentration of diluted nitric acid can remove fingerprints without harming the fingers.
A simple online search for information would not suffice to achieve this.
