With Benjamin's help,
Annan felt he was edging ever closer to the truth.
The different identities of the Idol Wizard did indeed separate with people's perceptions... but after all, in reality, the holder of these identities was the same person.
There must be intersections among "them."
Thus, if an ordinary person knew one identity and kept investigating by following the leads, it was possible to find the other identities—this was exactly the work Annan and his team were doing now.
Hiding one of the identities was indeed a difficult task.
There's a saying: if you would not be known to do anything, do it not.
To give one of the identities a credible persona, making people believe it's a new identity, you would have to perform many frequent and characteristic actions. And since these actions were widely known, evidence must have been left behind.