C1621 How to Investigate

"Then how can we investigate?" "What should we do?" Zhao Dajian said.

"I think it's very difficult. Since that person wants to do this, he must have made sufficient preparations to prevent others from investigating." Cao Li said.

I nodded my head, "Yes, but since the Secretary Sun has declared that it would be checked, I will do so. It's just that I don't know where to look for it myself