She vanished 17 months ago with no leads. Now, a volunteer cop has a troubling theory about what happened to her

Last spring, an off-duty LAPD cop named Mike Goldberg went to the movies at the Laemmle in North Hollywood with his wife.

At the theater, he spotted a flier for a missing 57-year-old Manhattan Beach woman named Nancy Paulikas, who suffered from advanced Alzheimer’s disease and had vanished on Oct....