The astrophysical origins of heavy elements like gold, silver, and uranium are unknown, though neutron star mergers (NSMs) have been confirmed as one such cosmic factory. Studying post-merger signals in the electromagnetic spectrum is invaluable for understanding how mergers produce these elements at both the microscopic and macroscopic scales. However, with the current low detection rates of NSMs, we invoke a different resource for observational data: metal-poor stars. Long after merger, metal-poor stars host in their spectra signatures of the historical explosive events that produced the heavy elements. Like unique fingerprints, these signatures unveil the distinct conditions under which the heavy elements were synthesized. This talk will discuss how stellar spectra—in lieu of direct merger detection—can act as a useful resource for studying NSMs and the mechanism at work that synthesizes the heaviest elements. I will show how investigating the cosmic factories of the heaviest elements by combining observation with theory is a step towards understanding both the Galactic evolution of the elements and the fundamental nature of dense matter.