Deathstroke was trying to piece it all together, but there were too many parts that defied common sense. So he could only do his best to treat it as an alternate-world mystery novel, like a new orthodox detective story—there was no need to worry about where those settings came from; he just had to reason according to the logic of the settings.
What was known: there were two Schillers. Although, in their words, they were the same person, they still ought to be marked as two characters. Deathstroke decided to call them "Agent Schiller" and "Conman Schiller" respectively.
These two characters had a trait: they could exchange souls through some unknown method and control each other's bodies. The process was so fast it was almost impossible to detect. And because they claimed to be one person, and the two bodies looked the same, when they controlled each other's bodies, they could pass themselves off very convincingly.
If everything Schiller had said was tentatively taken as true, then the flow of the whole affair could be deduced as follows:
Conman Schiller had created an artifact in the United States. For some unknown reason, the Justice League believed the artifact he had created was highly valuable. But by the time they discovered that value, Conman Schiller had already contacted the French arms dealer Hessinager and shipped the artifact out of the country.
On his side of the line, Hessinager was no good man either. When he learned that Conman Schiller had a batch of highly valuable artifacts of unknown origin, all he wanted was to get that batch of artifacts from Schiller and keep them for himself. So although he agreed to cooperate, in reality, he had long since secretly contacted Khaywen, the curator of the Egyptian Museum. And Khaywen made preparations