Modus operandi

Modus operandi (almost always used in the abbreviated form MO) is a Latin phrase, approximately translatable as "mode of operation", used in police work to describe a criminal's characteristic patterns and style of work.

It can be used to narrow down an investigation amongst a group of criminals with differing MOs. For example, a burgular may always use a back window, broken with a rock. If a group of known criminals are suspected to have commited a burgulary, then the characteristic modus operandi can be used to identify the burgular.

A criminal's MO can also be used in profiling, where the MO can give vital clues to a criminal's psychology.