I am a forensic pathologist and I can explain. The photograph shows the absence of vaginal secretions from the vic......uhhhhh......from the victim......uhhhhhh......hold on......UHHHHHHH. Yeah...what was the point of that?
These always leave a lot of questions. My only one at the moment is what the person with the camera was thinking with the 'upskirt' shot - the forensic purpose of knowing she had underwear on was what?