Lin Xixi is the only daughter of the Lin family. Previously, because she endangered Qin Yuji's life, Father Lin sent Lin Xixi back to America as a stopgap measure.
When Lin Xixi returned to M City from America, Chi Jingxuan was unsure. However, from the time Lin Xixi was caught until today, a month and a half had already passed. Yet, the Lin family only discovered today that their biological daughter was no longer in Washington. For both Chi Jingxuan and Qin Yuji, this was an unbelievable turn of events.
This time, after Lin Xixi committed such a vile act, Chi Jingxuan wouldn't let her off as easily as he did the last time.
Thus, when Father Lin inquired, Chi Jingxuan acted as though he knew nothing, letting them investigate on their own. If they couldn't find out, that would be their problem. If they did, then he would deal with them properly.