3. Blood traces are one of the most frequently found body fluids in cases of homicides,
battery, and sexual assault . However, blood present at a scene may not always be
relevant to the crime that occurred i.e. An individual may have cut themselves shaving
or while cooking and did not properly clean up.
Therefore, a major concern in criminal investigations is being able to distinguish between
bloodstains that are relevant to the crime versus those that are extraneous.
4. Fundamentals of Blood Aging
proteins, nucleic acids, lipid, and
carbohydrate exist at low
concentrations in the plasma
5. The iron ion forms bonds with the four nitrogen
atoms that are present in the heme compound
and a fifth bond with a segment of the Hb chain
,The sixth bond that occurs with this ferrous ion
is usually with O2
7. When all the oxyHb has
degraded to hemichrome,
presumptive blood tests
that rely on the presence of
oxyHb no longer work
The conversion process of oxyHb to metHb to
hemichrome has commonly been used as a method to
determine the TSD of bloodstains.
8. color chart
Solubility (fresh bloodstains:
rapidly dissolve / spectrum of
pure oxyHb), bloodstains aged
more water- insoluble/ spectrum
of metHb
HPLC (β-chains to γ-chains as a
measure ofTSD) X PEAK
Atomic force microscopy
(physical changes r to the
surface of red blood cells)
Electron paramagnetic
resonance spectroscopy (the
spin state of the iron ion in the
hemE)
Techniques for the analysis of red blood cells and hemoglobin
9. . Ultraviolet-visible (UV-Vis) absorption spectroscopy
changes to the Hb Soret band, which
has a max absorbance at 412 nm.
They discovered that this band
underwent a blue spectral shift, or a
shift to a lower wavelength, as the
bloodstain aged.
However, this technique is temperature
dependent.
The blue shift of the Soret band
occurred faster and had a longer shift
in bloodstains that were exposED to
heated conditions.
12. new bands at 667, 747, and 1248 cm-1
markers of Fe-O2 at bands at 419, 570 and
1638 cm-1 disappeared
377 cm−1 band (metHb) increased its intensity
in relation to 420 cm−1 (oxyHb marker);
intensity of band at 1252 cm−1 (part of the
amide III spectral region, assigned to random
coil) increased ,
intensity of bands at 637 (O2 marker band) and
1224 cm−1 (part of the amide III spectral
region, assigned to β-sheet) decreased;
13. decrease of the 1224 cm-1 band and
increase of the 1252 cm-1 band,
corresponding to transformation from β-
sheet into random coil (continue up to one
month since bloodstain deposition)
increase of the 970 cm-1 band’s intensity,
reflecting Hb aggregation
red shift of the band a520 cm -1 to 500
cm -1 (after one month elapsed since
deposition) with subsequent increase of its
intensity,
red shift of 676 cm-1 and 754 cm-1 bands
to 660 cm - 1 and 746 cm-1
14. diminishing of following bands over time
(non-existent in 1-year-old sample’s
spectrum): 345, 419, 1562, 1600, 1619,
1637 and 1653 cm-1
increase of the intensity of 440 cm-1
(novel spectral feature, non-existing in
spectra fresh blood)
15.
16. ATR FT-IR spectra of aged BF samples stored at ambient conditions
for one day, one week, one month, three months, fve months or
eight months
decreases in the characteristic bands of proteins, Amide I and Amide II
were identified in the spectra of aged blood, saliva and semen, indicating
degradation of the protein structures.
The spectra of aged urine and sweat showed possible influences from
differences in humidity, or water content, in the 3500-3100 cm−1 region.
However, significant decreases in the signals at approximately 1590 cm−1
and 1460 cm−1 in the aged urine spectra and approximately 1455 cm−1 in
the aged sweat spectra were indicative of the decomposition of urea.
17.
18. The decrease in peak intensity
at 1 640 cm-1 and 1 539 cm-
1 could be due to the
degradation of proteins and
other macromolecules
The increase in peak intensity
at 1392 cm1 (representing
COO stretching) may be caused
by break of peptide chain and
increment of free amino acids.
The PO2 peaks at 1232 cm1 ,
the increase in peak intensity
may be related to the
degradation and rupture of
sperm cells.
Editor's Notes
Heme is composed of a cyclic ring called porphyrin which is made up of four pyrrole entities that are linked by a methylene bridge, forming a unit called protoporphyrin IX. When this moiety is bound with an iron in its ferrous form (Fe2+) it is called ferroprotoporphyrin.
