The title is an editorialization: no government source (to my knowledge) has claimed that the IG photo was used to find the leaker, only that it served as a pie

The title is an editorialization: no government source (to my knowledge) has claimed that the IG photo was used to find the leaker, only that it served as a piece of data singling this suspect out among several. It’s much more likely that other, officially undisclosed, evidence led them to the suspect in the first place.