Answer: Mr. Castillo is serving a millitary as a citizen.
Step-by-step explanation:
How i got my answer:
Well we know jury means: a body of people (typically twelve in number) sworn to give a verdict in a legal case on the basis of evidence submitted to them in court. So we know Mr. Castillo is going to do a jury in court.
So that explains that Mr. Castillo is going to serve the millitary as a citizen.