While on their way back, Angor was still trying to figure out the possible secrets hidden by Lucas. It wouldn't be mere coincidence that so many supernatural individuals were looking for his traces.
Previously, Angor only wished to ask about Lucas to solve an insignificant suspicion bugging his mind, and whether he could learn a definite answer didn't matter. But after he saw other supernaturals involved in this matter… he felt his curiosity aroused.
Since he had Lucas' logbook, he might as well check some of the places mentioned in it.
"Lost Paradise City in the Anrum Monarchy…"
According to the logbook, Lucas fell into great despair because no one believed his stories. He then ended his own life at Lost Paradise City.
But if that was the case, then there was no way Lucas' corpse would show up at Devil's Water along with his logbook.