could not understand who would want to kill eric. >> reporter: the family had pointed detective dimitry ruvinriend, denise. >> we interviewed denise multiple times. >> reporter: ruvin's interest in denise picked up when he learned from the family that her romance with eric was on the rocks. >> he was with her probably about a year. and then after awhile he was just tired of being, i guess, bogged down by someone. denise told him that she and eric were talking about breaking up by mutual agreement. ruvin said she also acknowledged eric was dissatisfied with their relationship, giving the detective a theory to consider. older woman, younger man. and now, he wants to end it and maybe see somebody else. >> right. >> reporter: and that breeds jealousy and we know what that leads to. >> correct. jealousy leads to murder. >> reporter: while he continued to investigate denise, ruvin learned from residents in eric's building that there was a woman there he'd been dating for just a few weeks. >> that's why we wanted to talk to katrina. >> reporter: katrina ben came down to police headquarters for an in