Transient evidence is term used in criminal forensics to indicate elements of physical evidence that might be expected to degrade or disappear within a particular time frame."The FBI Process" Exploration Evidence and Investigation, Part II.http://www.teachingtools.com/solutions/Episode5FBI.htm As such, it is one of the five primary categories of physical evidence codified in Legal Medicine by the American College of Legal Medicine, along with conditional evidence, pattern evidence, transfer evidence and associative evidence.Legal Medicine, 7th Edition, page 636. While, in a sense, many types of evidence degrade with the passage of time (such as witness recollections, a victim's clothing, etc.), the term is specific to factors with an inherently limited period of existence. A bloodstain itself is not transient evidence, despite its mutable nature. The condition and appearance of that bloodstain at a given point of time would, however, be transient evidence.
