Biological Fluids, Fecal Matter, and Gastric & Lung Content
In the course of studying unknown materials, it is inevitable that questions of identification involving urine, saliva, blood and even fecal matter sometimes arise. The identification of gastric contents (i.e., the contents of stomachs) and lung contents are another specialized field that utilize information about the solids and fluids within them to draw conclusions about the circumstances, sequence of events that lead to death, or the location in which a death occurred. The identification and contents of fecal matter can also provide important information that can be used to substantiate or refute statements or establish facts in cases. Microtrace scientists have developed specialized expertise in the study of these substances through a combination of study, research, teaching, and casework.
Bodily Fluids and Residues
When examining unknown stains and residues, there are instances where a completely unknown material turns out to be of biological origin, while in other cases, there may be a suspicion that a biological fluid may be present. The identification of biological residues including blood, urine, saliva, semen, vomit, and fecal material can provide factual information to an investigation. While many laboratories offer a single assay for a given sample, our laboratory maintains a range tests with varying sensitivity and specificity so that we can apply the most appropriate test to the sample at hand. Our array of analytical approaches can be applied to virtually any sample, from an item of food to the smallest drop of residue. In other cases, it is beneficial to observe the spatial distribution of a stain. In these instances, the analysis can be tailored to the amount of material, the information needed, and the sample preservation requirements.
Gastric Contents, Vomit & Fecal Matter
To many, the study of fecal matter, vomit, and gastric contents are not the most palatable of subjects; however, analysis of these materials can provide a wealth of information. Over the years, Microtrace has both identified materials as fecal matter (or not) and studied the gastric contents of humans and animals to assist with death investigations and to determine how or where such events occurred. In these examinations, not only is it possible to identify the types of food present in the stomach, but it is also possible to search for and identify foreign substances such as poisons, drugs, etc.
The forensic analysis of lung content, both in human and animal lungs, can confirm the cause of death and provide information about the circumstances of death. For example, diatoms found in lungs along may indicate a drowning occurred in a freshwater environment. In addition, the composition of the water (e.g., fresh, brackish or chlorinated) can also check or confirm the circumstances of a drowning and whether it occurred in fresh water, salt water, or chlorine water. The specific circumstances of a case, the condition of evidence, and the composition of the water samples each have an impact on the ultimate information that can be obtained and significance of this evidence; however, the analysis of water from lungs, which we have conducted at Microtrace, can provide probative information in forensic investigations.
Related standardized methods: ASTM E1564, E1565, E1566