A suspect might also leave behind hairs or some kind of body fluid such as blood.

VOA: special.2010.05.05

They start as what are called vesicular lesions, or like blisters, where they're filled with a fluid.

这往往以出水痘开始,或者起水疱,里面充满液体

耶鲁公开课 - 生物医学工程探索课程节选

You can use PCR for fingerprinting as well, for looking in some unknown fluid for example, is a gene that I'm interested in there?

也可以用PCR做生物指纹鉴定,比如在一个未知溶液样本中,里面是不是有我感兴趣的那段基因呢

耶鲁公开课 - 生物医学工程探索课程节选