TITLE II. PRELIMINARY PROCEEDINGS
Rule 5. Initial Appearance
(a) In General.
(1) Appearance Upon an Arrest.
(A) A person making an arrest within the Republic must take the defendant without unnecessary delay before a judge, usually within 48 hours excluding weekends and holidays, unless a statute provides otherwise.
(B) A person making an arrest outside the Republic must take the defendant without unnecessary delay before a judge, unless a statute provides otherwise.
(2) Exceptions. If a defendant is arrested for violating probation or supervised release, Rule 32.1 applies.
Fair trial standards
Rights during investigation - arbitrary arrest or detention and deprivation of liberty
EDIT.