Why did the monsters chase Daniel?

[Kein]

**************************SPOILER**************************
They never capture him until the end, when Alexander tells them too. Until then I think they were just trying to kill him.

Yes I was talking about the part where you get captured, they got Daniel right there, why not kill him instead of just throwing him into a cell in bad condition ?

Because Alexander ordered them to bring Dan in prison? The game events states that clearly.