U.S. flag

An official website of the United States government, Department of Justice.

Determination of the Age (Time Since Deposition) of a Biological Stain

NCJ Number
Date Published
August 2008
84 pages
This study examined changes to hemoglobin spectral profiles, changes in enzymatic activity, and degradation to RNA in order to determine the time since deposition (TSD) or the age of dried bloodstains.
The study observed a previously unidentified hypsochromic shift (shift to shorter wavelengths) of the Soret band of hemoglobin, which allowed for distinguishing the differing age of bloodstains by minutes, hours, days, weeks, and months. The resolution and sensitivity of this method makes it particularly suited for use with forensic casework bloodstains. In addition, the loss of activity for six enzyme candidates was used to determine the age of dried bloodstains. Although this method was limited to determining month differences in bloodstain age, it provided initial support for the use of changes in enzyme activity in determining the age of a stain. Additional enzyme candidates may be identified that could improve the preciseness of this method. Initial work focused on examining degradation to mRNA in dried bloodstains, specifically the measurement of a progressive increase in the amount of degradation, so as to determine the time since deposition; however, all RNA-based methods provided inconsistent results and were therefore unsuccessful. The descriptions of materials and methods address the preparation of body fluid stains, environmental samples, humidity studies, RNA isolation, DNase I digestion, RNA quantitation, cDNA synthesis, polymerase chain reaction, gel electrophoresis, protein extraction and quantitation, UV-visible spectroscopy, and enzyme activity assays. 23 figures, 6 tables, 47 references, and appended listings of related presentations and publications

Date Published: August 1, 2008