DETECTION GUNSHOT RESUDUE ON CADAVEROUS LARVAE BY ICP OES
Name: LARISSA CAMPOS MOTTA
Type: MSc dissertation
Publication date: 28/03/2018
Advisor:
Name |
Role |
|---|---|
| WANDERSON ROMÃO | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| CARLOS AUGUSTO CHAMOUN DO CARMO | External Examiner * |
| GEISAMANDA PEDRINI BRANDÃO ATHAYDE | Internal Examiner * |
| MARIA TEREZA WEITZEL DIAS CARNEIRO LIMA | Co advisor * |
| WANDERSON ROMÃO | Advisor * |
Summary: The large increase in violent deaths, mainly in Brazil, and the increasing use of firearms
to commit such crimes, makes forensic ballistics associated with forensic entomology
major allies in criminal investigations. The concentrations of lead (Pb), barium (Ba) and
antimony (Sb), characteristic firearm residues (GSR - GunShot Residue), were
monitored in fly larvae (immature Chrysomya albiceps). The samples were collected
in a female pig corpse killed with three shots fired by a Taurus®, 40-caliber pistol at a
short distance (25 to 40 cm), two in the cephalic region and one in the abdominal
region, in a period of 2 to 12 days after death, during the winter, under the influence of
rainfall and high relative humidity of the air. Thus, the aim of this work was to evaluate
the applicability of the inductively coupled plasma optical emission spectrometry (ICP
OES) technique for the quantification of Pb, Ba and Sb from GSR in cadaveric larvae
in an uncontrolled environment, simulating a real case of homicide. The ICP OES
detect and quantify three trace elements of interest, WHERE the concentrations
remained practically constant during the putrefaction stage. The lowest concentrations
(Pb = 382.26 μg · L-1, Ba = 140.50 μg · L-1, Sb = 39.18 μg · L-1) and highest
concentrations (Pb = 522.66 μg · L- 1, Ba = 190.30 μg · L-1; Sb = 56.14 μg · L-1) were
found during the third and fifth postmortem days, respectively. The samples were also
analyzed by colorimetric test using sodium rhodizonate (Feigl-Suter reaction)
presenting negative result for all the solutions obtained from the immatures of
Chrysomya albiceps. One hypothesis for the concentrations uniformity of the three
elements is that according to the literature, Chrysomya albiceps larvae species may
play a role as an intraguild predator of larvae of other species of Diptera, in addition to
performing cannibalism. Thus, the ICP OES technique presents greater sensitivity in
the quantification of the elements of interest compared to the conventional colorimetric
test, showing to be a technique applicable to this type of matrix. The development of
such research is of great forensic importance and ICP OES is a technique that presents
potential for future application in cases of violent death, WHERE the victim is in initial,
moderate and advanced decomposition. In this regard, the development and
improvement of efficient methodologies are of great relevance for the elucidation of
crimes.
