now back to "dateline." ♪ >>> welcome back to "date line," sherry rasmussen had been murder inned in in the 1980s. from the outset, her parents told investigators about several run-ins sherry had with her husband's ex. now, decades later, a cold case detective was focusing his attention on that very same woman who also happened to be a member of the l.a.p.d. here's josh with more of "the smoking gun". >> for two decades the l.a.p.d. had one narrative for sherry rasmussen's murder. she was randomly killed by two men in a botched burglary. now science had rewritten the script and the once cold case was suddenly too hot to handle. the prime suspect, a l.a.p.d. detective named stephanie lazarus. but as detective jim nutall went through the original murder book, he found nothing on lazarus, even though she was the ex-girlfriend of sherry's husband. >> no indication she was spoken to? >> no. >> just one notion in the chronology of 1986, somebody had written, stephanie l, po, as police officer. as her name had come up but not as a suspect. she seemed to be someone above suspicion. stephanie