investigation unit

investigation and intelligence unit (law enforcement)

Federal Bureau of Investigation (FBI)

International Independent Investigation Commission - Lebanon (UNIIIC)

US Army Criminal Investigation Command

systematic investigation

targeted investigation

accident investigation

Accident Investigation and Prevention Section

accident investigation authority

accident investigation division

crash investigation procedure

safety investigation

safety investigation board

field investigation

air accident investigation

incident investigation

investigation anatomy

investigation authority

investigation tests

postflight investigation

space geological investigation

state conducting investigation

state instituting the investigation

investigation

background investigation

security сlearance check investigation

investigation branch

personnel security investigation

battery coolant unit / battery-coolant unit (BCU)

gear reduction unit / gear-reduction unit

position and navigation unit / position navigation unit (PNU)

pinch (a unit) out of a large unit