Hmmm, until she knows the true intent of why he took a picture (or if he even took one), I don't think it's naive to think it may indeed be innocent. I personally know of some of the horrible things that can happen in this world but we can't jump to terrible conclusions all the time or we'd go insane.

Ask him and/or the dc family what happened and than go from there. You may be getting yourself stressed out for absolutely no reason. Or he may have been taking a picture of something completely different or etc etc etc....the only way to know for sure is to ask!