Makes you wonder if the families have copies of the school photo's? If I remember right they always had a stamp with the studio on the backs.I am curious as well. I actually posted on a video covering these crimes that the killer might have been a photographer the schools hired for class photos. I did look up when school picture season is and depending on the school it falls in either Fall or Spring. The murders of the girls took place around the time school photos would be taken so I wouldn’t be surprised if it turns out the perp was suspected in CSAM cases during this time. The only problem is finding records of which photo studio they contracted with for the student photos because as I imagine the records might have been destroyed or lost over years which would mean it would be harder to find if there is a link between the girls’ schools and the killer as I suspect.
The DNA tests are frustrating. They have used it to rule a few people out if I remember right, but have not done anything checking for a link on Ancestry data bases.