Locard's Law of Exchange has been validated at every crime scene, without exception.
This arson case is a prime example.
After committing the murder, the culprit set a big fire at the scene, destroying all traces inside the room.
However, some traces outside the room still remained.
A partial footprint may be the key evidence to identify the suspect.
Returning to the team, Lu Chuan went straight to the crime scene investigation laboratory.
The first task was to identify the vehicle tire tracks.
From the preliminary analysis at the scene, the tire tracks found outside were the same as those found inside in terms of pattern and wear level, but differed in ground contact area.
This indicates that the electric vehicle left traces outside while carrying a load.
Now, Lu Chuan's task is to calculate the load of the electric vehicle based on the difference in tire ground contact area.
This is quite challenging.
