in·ves·ti·gate 
(ĭn-vĕstĭ-gāt′)
(ĭn-vĕstĭ-gāt′)v. in·ves·ti·gat·ed, in·ves·ti·gat·ing, in·ves·ti·gates
v.tr.
To observe or inquire into in detail; examine systematically: investigate a crime; investigate ways to use less energy; investigate whether the virus is contagious.
v.intr.
To make a detailed inquiry or systematic examination.
[Latin investīgāre, investīgāt- : in-, in; see IN-2 + vestīgāre, to track (from vestīgium, footprint).]
in·vesti·ga·ble (-gə-bəl) adj.
in·vesti·ga·to′ry (-gə-tôr′ē) adj.