Date of Submission


Document Type



Forensic Science


Claire Glynn, Ph.D.


DNA Typing, DNA Extraction, Degradation of DNA Overtime, DNA Yield


DNA, Blood, Saliva


In this research, we will examine the quantity of DNA over time. In John M. Butlers, "Fundamentals of Forensic DNA Typing", he charts out the average amount of DNA extracted from different bodily fluid samples. Examples include blood, semen, saliva, urine, etc. Though valuable, the values presented are in the cases of a fresh extraction of the sample. It is important to note that in most cases when DNA is being extracted from crime scene evidence, the samples are not fresh and have been degraded to some extent. On a crime scene, time is only one of the factors affecting the degradation of the samples; temperature, pH, and quantity of the sample are other factors that affect the quantity and quality of the DNA extracted. The purpose of the research is to evaluate how time alone can affect the amount of DNA received from samples of bodily fluid, specifically blood and saliva. Understanding the relationship between time and the quantity of DNA present can give investigators knowledge of how long a sample has been deposited at a crime scene. Results showed that though there was not a steady decline in the amount of DNA yielded from fresh samples to 4-month samples, the study shows that quantifiable amounts of DNA can still be recovered despite being under unfavorable conditions. Time is a factor of the quality of DNA present in a sample, but there is not an absolute relationship between time and DNA yield according to this study.