Trunk mysteries tended to lose their glamor if and when they were solved. Usually the shipper turned out be garden-variety murder (of a spouse, romantic rival, or robbery victim), a panicked abortionist who'd accidentally killed a patient, or a professional grave robber dispatching anatomical subjects to a medical college.
False alarms were also common. A conscientious baggage handler would notice a funky smell emanating from a trunk and report it. The contents would turn out to be some legitimately malodorous cargo like smoked halibut.
We don't do trunk mysteries anymore, of course, because nobody has a trunk now. And you'd have to choose your cadaver pretty carefully if you wanted to fit it into a carry-on bag.