Microscopical examination of particles on smoked cigarette filters.

Cigarette butts collected from crime scenes can play an important role in forensic investigations by providing a DNA link to a victim or suspect. Microscopic particles can frequently be seen on smoked cigarette filters with stereomicroscopy. The authors are not aware of previous published attempts to identify this material. These particles were examined with transmission and scanning electron microscopy and were found to consist of two types of superficial epithelial tissue, consistent with two areas of the lip surface. The particles were often composed of several layers of non-nucleated and nucleated epithelium with the former being the most common. It was further determined that both of these cell types are easily transferred from the lip. The results of this study indicate that the most visible source of DNA obtained from cigarette butts and other objects in contact with the lip may be lip epithelial tissue.