A perfect crime? To me, it's full of flaws!

The rating just came out... it will gradually rise!
[Suspenseful mystery + serial crime + ruthless action + slight humor + single female lead + light system]
Important notice: The first case is merely a preliminary step; the second is just the beginning!
The cases of the doll-hidden corpse, the murder and body disposal, and the serial revenge killings have all been written. The next case is the serial suicide by lying on the railway tracks.
Three murders, three female corpses, all naked, were sewn into custom-made oversized dolls and thrown into a bustling shopping mall and a trendy street.
The killer was extremely arrogant, not only deliberately leaving behind broken clues, but also staring directly into the camera to provoke the police under surveillance!
The S City police force is facing an unprecedented crisis, and criminal investigation experts from the provincial department are leading a team to provide support.
As the junior brother in charge of "carrying bags" in the team, Qi Feng silently activated the system when he saw the group of people at a loss.
In his view, the crime scene was no longer a dead end with no clues, but a series of huge red clue boxes!
A drop of blood in the crack of the steps, friction marks on the abandoned handcart behind the trash can, the subtle point of force in the suspect's limp left leg... Qi Feng followed the clues and pieced together a complete criminal profile!
"You think you've done a perfect job?" Qi Feng looked at him coldly. "Unfortunately, in my eyes, you're full of flaws!"
[Ding! Arrest successful, suspect profile upgraded to LV4!]