IDENTIFICATION AND AGE ESTIMATION OF BLOOD STAINS
Gerda Edelman ([email protected])Maurice Aalders, Ton van Leeuwen
Academic Medical Center, Biomedical Engineering and PhysicsAmsterdam, The Netherlands
Vicky Manti, Saskia van RuthWageningen UR, RIKILT Institute of Food Safety
Wageningen, The Netherlands
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BLOOD EVIDENCE
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Is it blood or ketchup?
Is it human blood?
Who’s blood is it?
Did he get hit by a
hammer?
How old is it?
BLOOD EVIDENCE
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I can test that using chemicals!
I have no idea!
Is it blood or ketchup? How old is
it?
HYPERSPECTRAL IMAGING
Combination of spectroscopy and digital imagingReflectance spectra of each pixelNon-destructive, fast, portableVis NIR wavelength range (400 -1000 nm)
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500 550 600 650 700 750 800-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
Wavelength (nm)R
efle
ctan
ce (
-)
500 600 700 800
10
20
30
Wavelength (nm)
Abs
orpt
ion
(mm
-1)
HbO2MetHbHC
Ex vivo
HEMOGLOBIN
04/21/23 WSC-08 7500 550 600 650 700 750 800-2
-1.5
-1
-0.5
0
0.5
1
1.5
Wavelength (nm)
Cor
r. r
efle
ctan
ce (
-)
1 min1 hour1 day1 week
Hb HbO2
Met-Hb
Hemichrome
oxygenation
oxydation
METHOD
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Specim pushbroom cameraReflectance spectra of:
Blood stainsOther substances (e.g. ketchup, lipstick, wine)
Dark correctionBackground correctionStandard Normal Variate correction
Absorption spectra of HbO2, MetHb and HCMie scatteringLight transport theoryNon linear least squares fit
Measured spectra Theoretical spectra
DATA ANALYSIS
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Blood Non blood
RESULTS
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500 600 700 800
-1
0
1
R2 =0.99827
Wavelength (nm)
Cor
r. r
efle
ctan
ce (
-)
FitBlood
500 600 700 800
-1
0
1
R2 =0.98086
Wavelength (nm)
Cor
r. r
efle
ctan
ce (
-)
FitKetchup
Goodness-of-fit Blood stains were identified
RESULTS
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Blood Non blood
0.7
0.75
0.8
0.85
0.9
0.95
1
Coe
ffic
ient
of
dete
rmin
atio
n (-
)
Sensitivity 100 %Specificity 85 %
AGE ESTIMATION
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500 600 700 800
-1
0
1
Wavelength (nm)
Cor
r. r
efle
ctan
ce (
-)
500 600 700 800
0
-1
1
Wavelength (nm)
Cor
r. r
efle
ctan
ce (
-)
Fresh blood
Old blood
Color change from red to brown, measured quantitativelyRelative contribution of HbO2, MetHb and Hemichrome changes in timeEstimated using least squares fit parameters
0 5 10 15 20 25 300
0.2
0.4
0.6
0.8
1
Age (days)
Rel
ativ
e am
ount
HbO2
MetHbHC
Relative amounts Age estimation
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AGE ESTIMATION
Ages of blood stains up to 2 years old were estimated. Accuracy decreases with age.Important NEW information about temporal aspects of crime.
METHOD
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FOSS NIR systems 6500 spectrometer
Reflectance spectra of:Blood stains on coloured cottonOther substances (e.g. ketchup, lipstick, wine)
Background correction
Library of 3 blood stains (1 day, 1 week, 1month old)
Compare R2 valuesbetween all blood stains and librarybetween other samples and library.
DATA ANALYSIS
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Sensitivity 100 %Specificity 100 %May reduce when other samples are added to the test set
RESULTS
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RESULTS
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Partial Least Squares RegressionTest set: blood stains on one colorTraining set: blood stains on all other colors
• Identification and age estimation of blood stains on coloured backgrounds by near infrared spectroscopy Gerda Edelman, Vicky Manti, Saskia M. van Ruth, Ton van Leeuwen, Maurice AaldersSubmitted to Forensic Science International
• Hyperspectral imaging of the crime scene for the automatic detection and identification of blood stains Gerda Edelman, Ton van Leeuwen, Maurice AaldersSubmitted to Forensic Science International
• Remote spectroscopic identification of blood stainsRolf Bremmer, Gerda Edelman, Tessa Dijn Vegter, Ted Bijvoets, and Maurice AaldersJournal of Forensic Sciences, 2011
• Age estimation of blood stains by hemoglobin derivative determination using reflectance spectroscopy Rolf Bremmer, Annemarie Nadort, Martin van Gemert, Ton van Leeuwen, Maurice AaldersForensic Science International, 2011
REFERENCES
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