Meaning of M.O.

In a lot of TV shows, the abbreviation M.O. is used to ask how the crime was committed. M.O. is actually an abbreviation from a Latin phrase. The phrase is Modus Operandi. Its translated as method or mode of operation. Method of operation is another way of saying/asking how the culprit committed the crime. Now, when you watch Criminal Minds, Law and Order, or any crime TV show, be sure to pay attention to the Modus Operandi!

References :

https://www.merriam-webster.com/dictionary/modus%20operandi

http://www.dictionary.com/browse/modus-operandi