Friday’s “Dateline” was the #1 show of the night in the target primetime A18-49 demo (1.7/3). Correspondent Josh Mankiewicz reported on a newlywed’s murder which led detectives to unravel a mystery that ended with a potential serial killer.

5.689 million viewers watched the show, vs. 4.681 million who watched newsmagazine competitor “20/20″ in the same timeslot. “Dateline” had its highest 18-49 rating in over a year and its biggest audience in six months — since June 1.