Red?

All of the titles have a red connection in reference to "Red John". It's the reason that Patrick Jane is consulting for the CBI: No Red John; no Patrick Jane in the CBI. The 次 bit is a spoiler so, read at your own caution!

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This continues to be the case, even in general cases not involving RJ, until the RJ story line is resolved at a later season down-the-line. In which case episode titles no longer have a red connection.