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Forensic Significance of Biological Fluids

A large variety of fluids are secreted inside and outside of the body. They include more than 28 different fluids such as blood, semen, saliva, milk, tears, sweat, urine, etc, as provided in the list below. Although, in principle, most of these fluids are capable of giving identity of a person, but in practice only a few of them actually have any serious forensic significance. In forensic practice, not only the identity of the suspect/victim is important, but other relevant issues such as drugs and chemicals consumed by the individual are also routinely considered.

In subsequent posts, the analytical part of these bio-fluids will be discussed in detail.

Biological Fluids

Amniotic fluid

•Aqueous humor and vitreous humor


•Blood serum

•Breast milk

•Cerebrospinal fluid

•Cerumen (earwax)

•Endolymph and perilymph



•Gastric juice



•Pericardial fluid

•Peritoneal fluid

•Pleural fluid




•Sebum (skin oil)



•Synovial fluid



•Vaginal secretion




Forensically Important Biological Fluids:-

The common biological fluid that a forensic science lab examines include, blood, semen, saliva, urine. In addition, examination of vaginal secretions and feces is also conducted in appropriate cases.


1. Useful to establish Identity: DNA typing

2. Useful in Identification of Drugs: Toxicological analysis

3. Linking the components of a crime: Crime Scene, Victim and Suspect



1. Useful to establish Identity: DNA typing 

2. Linking the components of a crime: Victim, Suspect & Crime Scene.



1. Useful to establish Identity: DNA typing 

2. Linking the components of a crime: Crime Scene, Victim and Suspect

3. Useful in Identification of Drugs: Toxicological analysis | Rarely



1. Best for Identification of Drugs / metabolites: Toxicological analysis

2. Rarely used for Identity: DNA typing



1. Useful to establish Identity: DNA typing

2. Can link the garment with the victim



1. Rarely used for Identity: DNA typing

2. Useful in wildlife forensic investigations: DNA typing, eating habits of animals, identification of metabolites.




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