Since Mu Yuze had cut off the interrogation room's surveillance in the first place, they could only communicate with each other through the earpiece. Li Zhi and Captain Rong had discussed it earlier and agreed that they'd better take some drastic measures against traitors – even though it was the last thing they had ever wanted. Nonetheless, the nature of their job compelled them to be prepared for the worst case scenario.
In case there was really a spy among the police, they did not wish to leave behind any surveillance footage that could put Wu Yuan's life in danger, and this live conversation would only be heard by a handful of trusted officers who handled the case.
