The subcategory of evidence deemed trace evidence is frequently seen in crime scenes, and while it is commonly the smallest evidence around, that doesn’t stop it from greatly contributing to the findings at the scene. Blood evidence may be categorized into this group in certain cases at crime scenes, especially in cases of transfer between two objects or people. In this study, the transfer of blood across both porous and non-porous substrates was examined to determine the persistence of blood across both substrates. The resulting stains after each trial of transfers were tested with a presumptive blood test commonly used in crime labs, the Kastle-Meyer test. Throughout all trials of the experiment, it was determined that blood on a non-porous surface typically dries faster as long as there isn’t a pooling effect, which hinders the ability for a stain to be continuously transferred and detected by Kastle-Meyer. Conversely, porous substrates are more likely to absorb and retain the blood in the material, allowing the blood to be released when pressure is applied, causing the stain to transfer more easily and result in a stain that will produce a positive Kastle-Meyer result.

Forensic entomology is an important field of forensic science that utilizes insect evidence in criminal investigations. Blow flies (Diptera: Calliphoridae) are among the first colonizers of remains and are therefore frequently used in determining the minimum postmortem interval (mPMI). Blow fly development, however, is influenced by a variety of factors including temperature and feeding substrate type. Unfortunately, dietary fat content remains an understudied factor on the development process, which is problematic given the relatively high rates of obesity in the United States. To study the effects of fat content on blow fly development we investigated the survivorship, adult weight and development of Lucilia sericata (Meigen; Diptera: Calliphoridae) and Phormia regina (Meigen; Diptera: Calliphoridae) on ground beef with a 10%, 20%, or 27% fat content. As fat content increased, survivorship decreased across both species with P. regina being significantly impacted. While P. regina adults were generally larger than L. sericata across all fat levels, only L. sericata demonstrated a significant (P < 0.05) difference in weight by sex. Average total development times for P. regina are comparable to averages published in other literature. Average total development times for L. sericata, however, were nearly 50 hours higher. These findings provide insight on the effect of fat content on blow fly development, a factor that should be considered when estimating a mPMI. By understanding how fat levels affect the survivorship and development of the species studied here, we can begin improving the practice of insect evidence analysis in casework.