Meaning:
"The usual suspects" are the people habitually suspected or arrested
following a crime. The phrase is usually used in regard to scapegoats
rather than actual perpetrators of the crime in question.
Background:
It was spoken by Captain Louis Renault, the French prefect of police,
played by Claude Rains in the 1942 U.S. film Casablanca.
But that was not the first. The expression and the extended "round up the
usual suspects" were in common use then in the police and underworld
communities of gangland New York.
...
'The usual suspects' is now as commonly used as other lines from the film
that were spoken by Bogart and which were much more quickly taken into the
public consciousness:
"Play it once, Sam. For old times' sake."
"Here's looking at you, kid."
"Of all the gin joints in all the towns in all the world, she walks into mine."
- www.phrases.org.uk
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The phrase could be very useful as people look for causes when things go wrong
as things always do. If networks at the Pentagon just went to pieces, it's
hackers, AI-armed this year, from Russia, China, or North Korea. If the
Chinese economy tanks, the usual suspects include the perennial overseas
reactionary forces. As we are entering the fire season in California, global
warming once again will be among the usual suspects along with run-of-the-mill
socialpathic pyros.