Chu Li knew that it was not the act of the Secret Guardians from the Imperial House.
He did not learn that news from the two Commanders.
In the case that they really did commit the act, they would certainly think about it when they faced him. But there was no trace of that matter in their minds at all, so Chu Li was sure that both of them were clueless about the matter.
Nonetheless, even though they were not the ones who did it, he could start looking for the Secret Guardians of the Imperial House.
The Secret Guardians from the Imperial House were very informative. It was possible that they had information about it. Hence, he had to personally look for some clues.
While the All-Seeing Divine Power was extensive, it was not omnipotent. Once someone died, their inner energy would dissipate and it would not be possible to locate them unless there were blood stains or hair on their bodies.