OTHER BODY FLUIDS

In addition to blood, other body fluids are often found at the scenes of crimes of violence. The other body fluids include semen, saliva, urine, perspiration pus, milk nasal mucus, and tears. Criminal laboratory attention is concerned primarily with semen and saliva. Like other evidentiary trace materials, all of these body fluids must be examined by examiners in the laboratory. If they are to be of any value, their initial handling by the investigator is most important.

When the word stain is used in the following material, it will refer to stains made by body fluids.

The same factors-the group specific substances-that make it possible to distinguish one blood from another, are present in the cells of every organ of the body and in almost every body fluid

Medical researchers originally demonstrated the presence of the grouping factors by examining known wet specimens under ideal laboratory conditions. They discovered, for example, that the concentration of the grouping factors in saliva and semen secretions was relatively high and that the concentration in tears, urine, and perspiration was very low. Following medical recognition of the results of this research and the standardization of identification techniques, the identification procedures were applied to stains of such fluids when encountered in medicolegal cases.

A secretor is an individual whose body fluids, as well as blood, may be grouped. A nonsecretor is an individual whose blood may be grouped, but whose body fluids may not be grouped.

The relationship of secretors and nonsecretors is approximately 80 percent to 20 percent respectively. The saliva is the most suitable material for distinguishing secretors from nonsecretors. It is easy to obtain, and if the individual is a secretor, the relatively high concentration of group specific substances will be easily noted. If group specific substances are present in the saliva of an individual, the substances will usually be present in almost every other fluid of that individual's body.

In criminal cases, body fluids usually appear as stains on clothing, bedding, upholstery, or similar objects. In examining a body fluid stain, the techniques and methods of identification are the same as for bloodstains, but identification is more difficult because of the nature of the stain, its age, and the presence of interfering factors. When handling evidence on which stains may have been caused by body fluids, you should exercise the same precautions prescribed in handling bloodstains.

Identification

Group substances in liquid or dried saliva and some other body fluids may be classified into groups A, B, AB, or O.

As with a bloodstain, the identification of a body fluid stain may be negative, or an inclusive opinion may be reached Nevertheless, the possibility that valuable investigative leads may result from the expert examination of a body fluid stain should not be overlooked.

For example, if a dried saliva stain is found that contains group substances, the stain could not have been derived from an individual whose saliva does not contain these substances. However, if the dried stain is free of these substances, two possibilities are present: (1) the saliva came from a person who is a nonsecretor, or (2) the specimen of saliva is free of the grouping substances because of contamination or deterioration, and a definite opinion is not possible.

Semen can be typed with some individuals when the specific factors of the blood are carried in the fluid Saliva normally provides a reliable typing. The typing of urine, and other body fluids, is subject to many more variables, and consequently, reliable typing is more difficult.

A known saliva sample should be obtained from suspects and victims involved to determine if they are the secretor(s), and if so what their blood types are. This is done by having each person chew on a separate 2-inch square piece of thin gauze for about 5 minutes at the back of the mouth. The gauze is then allowed to air-dry completely. It is then placed in a sterile container and sent to the laboratay.

If the gauze is not dried, enzymes in the saliva will destroy the blood group substances, which may lead to an incorrect result in subsequent testing. Blood samples should also be obtained and submitted.

Other Stains

Objects suspected of bearing stains from body fluids other than semen should be handled with the same precautions and transmitted to the criminal investigation laboratory in the same manner as bloodstained articles.