"Telltale evidence" refers to clear and undeniable proof or clues that reveal or expose something. It is evidence that reveals a certain fact or situation beyond any doubt or ambiguity. Full definition
«We were looking for orbiting pairs of supermassive black holes, with one offset from the center of a galaxy, as telltale evidence of a previous galaxy merger,» said James Condon, of the National Radio Astronomy Observatory. (public.nrao.edu)
«We were looking for orbiting pairs of supermassive black holes, with one offset from the center of a galaxy, as telltale evidence of a previous galaxy merger. (ibtimes.com)
The inspector will also check for signs of insect damage by termites and carpenter ants which will leave telltale evidence. (stockmonkeys.com)