Aims and objectives
The tools used in cases of dismemberment cause specific marks,
defined tool marks,
on the victims [1,2].
Saws,
which are considered complex tools,
can cause marks on the bone which are usually defined as “false starts” and are characterized by several features such as shape,
set and teeth per inches (TPI).
Different techniques can be applied to analyze false starts on bones,
including optical [3–5] and digital [6] microscopy,
scanning electron microscopy (SEM) [7,8],
environmental scanning electron microscopy (ESEM) and epifluorescence macroscopy [9].
Recently,
very...
Methods and materials
Three types of saws (saw1,
saw2,
saw3),
differing for set (saw1 and saw2=alternating; saw3=wavy) and shape (saw1=crosscut; saw2 and saw3=ripcut) were selected.
For each type,
two saws differing only for TPI (saw1_8TPI;saw1_11TPI; saw2_8TPI; saw2_10TPI ; saw3_18TPI; saw3_24TPI) (Fig 1) were used to perform 84 SMs (i.e.,
14 with each saw) on as many human bone samples (e.g.,
phalanx).
Each sample was scanned by MicroCT applying the following parameters: 14 μm isotropic voxel size,
51 Kv,
194 uA,
exposition time 6050 ms,
rotation step 0.7,
frame...
Results
Using the morphological assessment,
all SMs were attributed to the correct saw type (i.e.,
28 SMs each) (Fig 3).
Concerning the quantitative assessment,
saw1_8TPI and saw1_11TPI showed statistically significant differences for the angles and the mean between the angles (p<0.001; 100% accuracy,
each) (Table 1).
KW allowed a perfect distinction between saw2_8TPI and saw2_10TPI (i.e.,
p<0.001; 100% accuracy) (Table 2).
No differences occurred between saw3_18TPI and saw3_24TPI for any metric (Table 3).
Thus,
our results demonstrated that a morphometric flow-chart,
based on the morphologic and...
Conclusion
The results of the hereby presented innovative and experimental study propose a new approach to investigate saw marks on bone,
which is expected to improve the identification of the tools used in cases of dismemberment.
Future studies including lesions caused by different operators,
samples altered by fire,
putrefaction or exposure to physical or chemical agents are necessary prior to the application of the proposed flow-chart in forensic caseworks.
References
Pelletti G,
Viel G,
Fais P,
et al.Micro-computed tomography of false starts produced on bone by different hand-saws.Leg Med (Tokyo) 2017;26:1–5.
Symes SA,
Berryman HE,
Smith OC.
Saw marks in bone: introduction and examination of residual kerf contour.
in: K.J.
Reichs (Ed.),
Forensic Osteology: Advances in the Identification of Human Remains,2nd ed.,
Charles C Thomas,
Springfield,
1998,
pp.
393–395.
Andahl RO.
The examination of saw marks.
J Forensic Sci Soc 1978;31–46.
Bailey JA,
Wang Y, Van de Goot FR,
et al.
Statistical analysis of kerf...