Lu Wu was being watched from the first day his freedom was restricted.
The ones who set their sights on him were the old man Zhao Kai Ming with the fishing plan and his lieutenant, the middle-aged He Tianguang.
At the time, perhaps due to the recent embarrassment, Zhao Kai Ming was somewhat mentally unbalanced.
He had just watched a bit of the interaction between Lu Wu and Li Kai and immediately determined there was something off about Lu Wu.
In his own words at the time,
"I guarantee you, this kid is definitely up to something fishy!"
He Tianguang was skeptical even then.
"This kid probably isn't a problem. If there were any issues, he wouldn't have let Li Kai organize the exchange; that would only make it easier for him to get caught."
"You don't understand, this is called setting a persona!