CONSTITUTION OF BOTSWANA
CHAPTER II - Protection of Fundamental Rights and Freedoms of the Individual (ss 3-19)
5. Protection of right to personal liberty
(2) Any person who is arrested or detained shall be informed as soon as reasonably practicable, in a language that he or she understands, of the reasons for his or her arrest or detention.
Fair trial standards
Rights during investigation - access to interpreter and translation if questioned in other language
Rights during investigation - informed of belief that crime has been committed
EDIT.