It can be used to find out what process was used to tan leather by determining what metals are in the leather. This information is then used to make standards to determine how a hide was tanned and how long ago it was tanned. For example, if a tiger skin has been sent to the Lab and the owner claims that it was killed by a great, great grandfather long before tigers were an endangered species, a scientist can compare what he finds on the tiger skin using the XRF to the set of standards for tanned hides. If the scientist finds that the tiger skin was tanned using a metal such as aluminum, he knows that it was recently tanned as compared to being tanned years ago by a great, great grandfather since the aluminum process is a relatively recent one. Bob not only uses the XRF to create reference samples so that a scientist at the Lab can determine what type of tanning process was used on leather, but also to determine if two pieces of paper are identical.
Paper is treated with one of four or five different kinds of metal.
Data from the XRF can be used to determine the amount and type of metal used to process two pieces of paper and by comparing the results, a scientist can decide if the two samples came from the same piece of paper or same tablet. Another project that Bob has completed for the Lab is a statistical program that allows agents in the field to establish the time a deer died by changes in its body temperature. He took data from agents in the field, compiled it, applied statistical analysis to it and then wrote the program. This type of analysis has been done before, but not in such depth. Bob began as a volunteer at the Forensics Lab in February, 1991.