Cold Case (2003) - 4x09 - Lonely Hearts

Lilly and the team delve into the world of a modern day lonely hearts club when a handsome man commits suicide while watching a tape of an unattractive woman whose murder went cold in 1989.

The connection between the victim, Ramon, and the deceased, Martha, was a video dating service, the hunting grounds for a "Don Juan" who preyed on women unlucky in love. Lilly discovers that, once united, this unlikely couple left a trail of bodies behind them and that the woman, whose romance novel notions of love blinded her to her paramour's evil ways, may not have been as innocent as she seemed.