1. bugs can help solve a crime
2.teeth are typical identifiers on corpses
3. hair roots can identify gender
bonus: This one is random, but glitter is PERFECT when it comes to evidence. For one, it’s easily transferable from one person to another. Two, since it’s something not so obvious (unlike blood), suspects probably won’t wash it off immediately, if it even comes off their bodies at all. And lastly, it’s easy to fine with the shine of a flashlight. The likelihood that a crime scene involves glitter is not very likely, but… the more you know.