IMO every article of clothing was probably not released to the public for various reasons. 1) who, other than the person who placed her there could identify her underpants or pull-up (I am a mother and no one besides me usually see these items). 2) the shirt may or may not have been present. I've seen my children go to bed dressed in a top and magically they've wiggled out of it by morning. I've also seen my girls decide to sleep in top or bottom only on occasion. 3) if the shirt was present, it may be withheld so that it can be used to confirm information when they interview potential people later on (as the color and design was not public knowledge). They may have weighed which article of clothing would be more memorable to people who knew this child but holding back an article to further the investigation. All are my opinion of course.
I will say that I I don't know that worrying where her underwear and shirt are really leads me to any useful information to help determine what happened to this little angel. I think her outfit becomes useful only if you recognize her at this point, I pray the clothing has sparked a memory for someone that's useful.
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