|Buffy the Vampire Slayer: Passion (1998) [Jenny Calendar]: Neck reportedly snapped by David Boreanaz after he chases her through the school; her body is shown again afterwards when Anthony Head discovers her in his bedroom. (I haven't seen this episode myself.) (Thanks to Matt, Germboygel, and Alex)
CSI: You've Got Male (2001) [Joan Marks]: Neck snapped by Nick Chinlund. Her body is shown (along with Amanda Wyss') near a drainage pipe, then in the morgue when William Petersen and Robert David Hall examine her; the murder is shown in flashback towards the end of the episode.