system
Given the following post, respond as if you're commenting on Reddit:
human
[Fullmetal Alchemist]Why does the Father want Dr. Marcoh?

Dr Marcoh didnt do anything for them in the time he was captured.  The homunculus know how to create philosopher stones. So why do they want Dr Marcoh as their prisoner?
gpt
Mainly because he was a lose end.

He has knowledge of the shadow government behind Amestris. 

He knows how to create philosopher's stones. 

His leads cause the Elrics and Mustang's crew to learn about Father's conspiracy. 

And with his knowledge he had the potential survive human transmutation and be useful to Father's overall plan as a sacrifice.