IDENTIFICATION AND AGE ESTIMATION
OF BLOOD STAINS
Gerda Edelman (G.J.Edelman@amc.nl)
Maurice Aalders, Ton van Leeuwen
Academic Medical Center, Biomedical Engineering and Physics
Amsterdam, The Netherlands
Vicky Manti, Saskia van Ruth
Wageningen UR, RIKILT Institute of Food Safety
Wageningen, The Netherlands
4/6/2015
WSC-08
1
BLOOD EVIDENCE
Is it human
blood?
Who’s
blood is it?
Did he get
hit by a
hammer?
Is it blood
or ketchup?
4/6/2015
How old is
it?
WSC-08
2
BLOOD EVIDENCE
I can test
that using
chemicals!
I have no
idea!
Is it blood
or ketchup?
4/6/2015
How old is
it?
WSC-08
3
HYPERSPECTRAL IMAGING
Combination of spectroscopy and digital imaging
Reflectance spectra of each pixel
Non-destructive, fast, portable
Vis NIR wavelength range (400 -1000 nm)
2
Reflectance (-)
1.5
1
0.5
0
-0.5
-1
-1.5
-2
500
550
600
650
700
750
800
Wavelength (nm)
4/6/2015
WSC-08
4
Can we distinguish blood from other substances?
BLOOD STAIN IDENTIFICATION
4/6/2015
WSC-08
5
HEMOGLOBIN
In vivo
oxygenation
Hb
HbO2
1 % oxydation
Met-Hb
4/6/2015
WSC-08
6
HEMOGLOBIN
Ex vivo
oxygenation
Hb
HbO2
MetHb
HC
-1
Absorption (mm )
30
HbO2
oxydation
Met-Hb
20
10
500
600
700
800
Wavelength (nm)
1.5
Hemichrome
Corr. reflectance (-)
1
0.5
0
-0.5
-1
1 min
1 hour
1 day
1 week
-1.5
4/6/2015
WSC-08
-2
500
550
600
650
700
Wavelength (nm)
750
800
7
METHOD
Specim pushbroom camera
Reflectance spectra of:
Blood stains
Other substances (e.g. ketchup,
lipstick, wine)
4/6/2015
WSC-08
8
DATA ANALYSIS
Measured spectra
Theoretical spectra
Dark correction
Background correction
Standard Normal Variate
correction
4/6/2015
Absorption spectra of HbO2,
MetHb and HC
Mie scattering
Light transport theory
Non linear least squares fit
WSC-08
9
RESULTS
Non blood
Fit
Blood
Corr. reflectance (-)
Corr. reflectance (-)
Blood
1
0
-1
R2 = 0.99827
500
600
700
Fit
Ketchup
1
0
-1
800
500
Wavelength (nm)
4/6/2015
R2 = 0.98086
600
700
800
Wavelength (nm)
WSC-08
10
RESULTS
Goodness-of-fit
Blood stains were identified
Sensitivity 100 %
Specificity 85 %
1
Coefficient of determination (-)
0.95
0.9
0.85
0.8
0.75
0.7
Blood
4/6/2015
Non blood
WSC-08
11
Can we estimate the time of bleeding?
BLOOD STAIN AGE ESTIMATION
4/6/2015
WSC-08
12
AGE ESTIMATION
Corr. reflectance (-)
Color change from red to brown, measured quantitatively
Relative contribution of HbO2, MetHb and Hemichrome changes in time
Estimated using least squares fit parameters
Fresh blood
1
0
-1
500
600
700
800
Corr. reflectance (-)
Wavelength (nm)
Old blood
1
0
-1
500
600
700
800
Wavelength (nm)
4/6/2015
WSC-08
13
AGE ESTIMATION
Relative amounts
Age estimation
1
HbO2
MetHb
HC
Relative amount
0.8
Ages of blood stains up to 2
years old were estimated.
Accuracy decreases with age.
Important NEW information
about temporal aspects of
crime.
0.6
0.4
0.2
0
0
4/6/2015
5
10
15
20
Age (days)
25
30
WSC-08
14
AGE ESTIMATION
The presence of blood of two different ages was proved.
4/6/2015
WSC-08
15
What if people wear dark clothing?
NIR SPECTROSCOPY
4/6/2015
WSC-08
16
DARK BACKGROUNDS
Visible color image
4/6/2015
Near infrared image (800 nm)
WSC-08
17
NIR SPECTROSCOPY
Absorbance spectra of coloured cotton
4/6/2015
WSC-08
18
Can we distinguish blood from other substances?
BLOOD STAIN IDENTIFICATION
4/6/2015
WSC-08
19
METHOD
FOSS NIR systems 6500 spectrometer
Reflectance spectra of:
Blood stains on coloured cotton
Other substances (e.g. ketchup, lipstick, wine)
4/6/2015
WSC-08
20
DATA ANALYSIS
Background correction
Library of 3 blood stains (1 day, 1 week, 1month old)
Compare R2 values
between all blood stains and library
between other samples and library.
4/6/2015
WSC-08
21
RESULTS
Blood
Hemoglobin, albumin, globulin
Absorbance (a.u.)
Water
4/6/2015
WSC-08
22
RESULTS
Hemoglobin, albumin, globulin
Non blood
Absorbance (a.u.)
Water
4/6/2015
WSC-08
23
RESULTS
Sensitivity 100 %
Specificity 100 %
May reduce when
other samples are
added to the test set
4/6/2015
WSC-08
24
Can we estimate the time of bleeding?
BLOOD STAIN AGE ESTIMATION
4/6/2015
WSC-08
25
Absorbance (a.u.)
AGE ESTIMATION
4/6/2015
WSC-08
26
RESULTS
Partial Least Squares Regression
Test set: blood stains on one color
Training set: blood stains on all other colors
4/6/2015
WSC-08
27
NATIONAL NEWS
4/6/2015
WSC-08
28
4/6/2015
WSC-08
29
REFERENCES
•
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 Aalders
Submitted 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 Aalders
Submitted to Forensic Science International
•
Remote spectroscopic identification of blood stains
Rolf Bremmer, Gerda Edelman, Tessa Dijn Vegter, Ted Bijvoets, and Maurice Aalders
Journal 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 Aalders
Forensic Science International, 2011
4/6/2015
WSC-08
30