Yes it would! It can be hidden as ingeniously as necessary to justify the length of time spent looking for it—for example, tucked inside a preserved organ and detectable only on very close examination, or require recognition that the stitching technique used to sew something up is one taught to younger initiates now but was out of fashion when Berenike actually died, or whatever other detective-y nonsense you'd like to incorporate to make it clever—but Ilias will ultimately be able to find something similar in design to a phylactery that appears to contain red lyrium embedded in the corpse. Breaking it open would obviously be unwise.