Criminal Minds S10E17 “Breath Play” First aired March 11, 2015 IMDB
The second episode of Criminal Minds to deal with BDSM (that I know of) is “Breath Play”.
“Breath Play” treads much of the same ground as the earlier episode “Limelight”, though at least in this case there are actual victims from the beginning. A serial killer is strangling women to death and leaving them tied to their beds. Somehow, the killer is welcomed into the homes of his victims.
Examining the bodies reveal that the victims were tied to their beds and strangled for hours before their deaths. Dr. Reid speculates, in one of the leaps of logic that seems typical of this series, that this is actually about erotic asphyxiation, or breath play.
Another crime scene leads of the discovery of an extremely popular erotic novel called Bare Reflections, a knock-off of Fifty Shades of Grey. All of the victims had the book, and the “saucy texts” found on the victim’s phone were direct quotes. However, if the book is that popular, it increases the likelihood that it’s just a coincidence and not the key clue.