The fact that such crucial evidence as personal items could be stolen indicates that Jing Tong was indeed no ordinary person.
For many years, Dark Street's business operations were intricate and deeply entrenched. Although the Leng Family had always been in control, it cost them a great deal of energy and price. It was a violent industry and concurrently the darkest and dirtiest of industries.
Without ruthless measures, it absolutely couldn't continue; wave after wave of suppression, only the Leng Family could stand firm.
Outsiders only knew of Shi Cin as the behind-the-scenes figure, but no one could have guessed that the real controllers of Dark Street were the Leng Family. And the one in charge of Dark Street was Leng Yi, though once Leng Yi's watch had passed through Jing Tong and landed in the hands of the police, then Leng Yi would be implicated.
By then, sacrificing a Leng Yi wouldn't entirely sever the connection with Dark Street.