Evaluation of Parameters for Estimating the Postmortem Interval of Skeletal Remains Using Bovine Femurs: A Pilot Study

Abstract

The postmortem interval (PMI) of victims is a key parameter in criminal investigations. However, effective methods for estimating the PMI of skeletal remains have not been established because it is determined by various factors, including environmental conditions. To identify effective parameters for estimating the PMI of skeletal remains, we investigated the change in bone focusing on the amount of DNA, element concentrations, and bone density that occurred in the bone samples of bovine femurs, each maintained under one of five simulated environmental conditions (seawater, freshwater, underground, outdoors, and indoors) for 1 year. The amount of extracted mitochondrial DNA (mtDNA; 404 bp fragment) decreased over time, and significant DNA degradation (p < 0.01), as estimated by a comparison with amplification results for a shorter fragment (128 bp), was detected between 1 month and 3 months. Eleven of 30 elements were detected in samples by inductively coupled plasma optical emission spectrometry, and Na and Ba showed significant quantitative differences in terms of environmental conditions and time (p < 0.01). This preliminary study suggests that the level of DNA degradation determined by real-time polymerase chain reaction and element concentrations determined by inductively coupled plasma optical emission may be useful indices for estimating the PMI of victims under a wide range of environmental conditions. However, this study is a limited experimental research and not applicable to forensic cases as it is. Further studies of human bone with longer observation periods are required to verify these findings and to establish effective methods for PMI estimation.

Estimation of Late Postmortem Interval: Where Do We Stand? A Literature Review

“…Bone samples were divided into four groups based on PMI, and it was found that the expression of target microRNA in bone samples from group 1 (PMI < 1 month) was statistically different from other groups. Other research focused on microRNA with similar conclusions and shorter PMI [48][49][50].…”

Recognition of the Presence of Bone Fractures Through Physicochemical Changes in Diagenetic Bone

“…Three elemental measurements of the outer edge of the cortical bone were taken per sample and averaged to give one overall reading per sample. Eight elements were selected using current literature 34 , 52 as guidance; calcium and phosphorus to represent bone minerals, potassium, sodium, and iron to represent bodily fluids, and magnesium, zinc, and barium to represent trace elements. For analysis, the mass (%) of each selected element was calculated using analytical software in standardless quantitative mode.…”

“…41 A loss in iron has also been observed <12 months PMI and has been associated with the breakdown of blood cells. 34 Studies have also noted changes to zinc, 52 manganese, and magnesium 41 occurring over time.…”

“… 38 , 39 , 41 , 47 , 48 Bone exchanges elements with the deposition environment and changes to the elemental composition of bone are found in both archaeological contexts, 49 – 51 and short timescale studies. 34 , 36 , 39 , 41 , 52 , 53 Various elements have been studied as part of diagenesis research, particularly calcium and phosphate due to their presence in bone minerals. Iron, sodium, and potassium are related to bodily fluids, while other elements are present in trace amounts.…”