Complex sentence: On December 10,1977 a Sacramento Sheriffs operator received a call threatening an attack, the call was recorded and the caller was subsequently identified as the same individual who had made the "Merry Christmas" call.
Split into simpler sentences: On December 10,1977 a Sacramento Sheriffs operator received a call threatening an attack. The call was recorded, and the caller was subsequently identified as the same individual who had made the "Merry Christmas" call.