This article is the first in a series relating to the application of microscopy to forensic science. As such, the article is intended to be purely introductory in nature. Future articles will be specific both as to the forensic challenge and the solution as allowed by the creative application of microscopy.

Microscopy has played an integral part in forensic science since the early part of this century. In 1928, E. Locard established the practical and theoretical underpinnings of the microscopic examination of trace amounts of evidence. The “exchange principle of evidence” was so developed:

Whenever two objects come into contact there is always a transfer of material. The methods of detection may not be sensitive enough to demonstrate this or the decay rate may be so rapid that all evidence of transfer has vanished after a given time. Nonetheless, the transfer has taken place.