People disappear without a trace for a variety of reasons. That’s a different kind of “missing” that is more than simply being unable to find them in records. If your relative disappeared–either intentionally or as the victim of some type of crime–newspaper accounts or court records may provide additional detail. If the relative just up and left, there may be divorce records as well. It’s also possible that some reference to the disappearance may be mentioned in probate records for an estate in which the missing person was an heir.