Le Yu's first suspect was White Night, since Qin Leyin's bright red hair was just too recognizable; even if Le Yu could use the Formless Battle Technique to change his face, there was absolutely no way to turn his hair into another color.
A few days had gone by, so the news from Xuanzhu County should have already reached White Night in Yanjing. As long as they knew "the Shi and Qin families successfully escaped Xuanzhu," "Qin Leyin is closely connected with Jing Zhengwei," and "the Linhai Army's military funds got hijacked," they'd naturally start suspecting Qin Leyin.
The worst possible scenario would be if someone from the Shi family betrayed them and exposed the fact that the Shi and Qin families had intercepted the military funds.