This and the next episode "The Longest Night" (which is essentially the second half of this episode) both have soundtracks consisting solely of Leonard Cohen songs.
There is no end quote in this episode, as it ends with: To Be Continued.
The serial killer is being called The Prince of Darkness. In the movie Legend (1985) Tim Curry played a devilish creature named Darkness.
Robert Davi (Detective Kurzbard) and Eric Close (Detective Spicer) also played FBI agents on other television shows. Davi was the lead profiler on Profiler (1996), while Close played an FBI agent on Without a Trace (2002), which also deals with profiling.