in·ves·ti·ga·tion 
(ĭn-vĕs′tĭ-gāshən)
(ĭn-vĕs′tĭ-gāshən)n.
1. The act or process of investigating: a politician under investigation.
2. A careful examination or search in order to discover facts or gain information. See Synonyms at inquiry.
in·ves′ti·gation·al adj.