What is the name of the episode where Ralph Cifaretto is killed?

The episode where Ralph Cifaretto is killed is “Whoever Did This,” the ninth episode of The Sopranos' fourth season.

Tony Soprano confronts Ralph after a stable fire kills Pie-O-My, the racehorse Tony has grown attached to. Tony suspects Ralph arranged the fire to collect insurance money, although Ralph denies causing it. Their argument becomes violent, and Tony beats and strangles Ralph to death. Christopher Moltisanti later helps Tony dismember and dispose of the body.

The episode's title comes from Tony's phrase “Whoever did this,” which he uses while discussing the fire and Ralph's death. The wording deliberately reflects Tony's attempt to frame the killing as a response to the stable fire rather than openly acknowledge that he murdered Ralph.

Ralph's death also connects to an earlier episode, “University,” in which he kills Tracee, a young dancer at the Bada Bing. Tony's anger over Tracee's murder contributes to the emotional weight of the confrontation, even though the immediate trigger is Pie-O-My's death.