I've seen "Crime Scene Investigator" kits for kids, but didn't find them impressive. Doje's Forensic Supplies http://www.dojes.com/ is for adults ~ for members of the forensic community specifically. Some of their products, like Cyanoacrylate or Phenolphthalein, aren't in most of the "children's" toy kits, and you may need to perform some online research to ascertain the uses to which you could put these things. For inquiring minds, this might be a useful place to peek.
more