police not giving any details of arrested people

File writ petition (Habeas Corpus).

As per your query, that you must appoint a good lawyer and proceed to file a writ of Habeas Corpus. A writ of habeas corpus is used to bring a prisoner or other detainee (e.g. institutionalized mental patient) before the court to determine if the person's imprisonment or detention is lawful.

A habeas petition proceeds as a civil action against the State agent (usually a warden) who holds the defendant in custody. Therefore, it will tend the court to order the police to present the detainees (you're relative) before the court.

Hope It Helps!

Regards
Kevin M. Paul