Presentation on investigations conducted for Fingerprint Inquiry Scotland

1
Presentation on investigations conducted for
Fingerprint Inquiry Scotland

• Dr Steve Bleay
• HOSDB Sandridge
• November 2009

2
Presentation outline

• The HOSDB Manual
• Analysis of marks
• Y7
• QI2
• XF

3
The HOSDB Manual
4
The HOSDB Manual

• Best practice guide for fingerprint development
  endorsed by ACPO
• Provides information on development techniques
  and processing routes for different types of
  surface

5
The HOSDB Manual

• Used in the fingerprint laboratories of all UK
  police forces (and many others worldwide)
• Processes selected according to their
  effectiveness in developing fingerprints, taking
  into account the health and safety issues
  associated with their operational use
• Recommendation of a particular process for
  operational use follows extensive trials of the
  process in both laboratory and operational
  environments
• Not mandatory to follow guidance there will
  always be scenarios that are not fully covered by
  advice given and operational constraints may
  require use of alternative techniques and/or
  sequences

6
The HOSDB Manual

• Use of depletion series
• Multiple contacts from a single finger, usually
  6-10 although some very sensitive techniques
  required 18
• Test of how sensitive technique is to small
  amounts of residue
• Fingerprints split wherever possible so direct
  comparisons can be made

A
B
A
B
7
The HOSDB Manual

• Some techniques/surfaces are incompatible with
  split fingerprints

• the edge disrupts the swish of a brush used for
  powders and can also damage fibres
• Solvents can creep under edges
• Surfaces can be difficult to split or can
  delaminate
• In these cases can use multiple donors on single
  plate

Donor
1
2
3
4
5
6
1
2
3
4
5
6
Fingerprint Depletion
7
8
9
8
The HOSDB Manual
Surfaces representative of the scenarios for
operational use
Donors a representative cross section (male,
female, young, old..)
Ages typically 1 day, 1 week, 1 month
9
The HOSDB Manual
Age/ environmentally condition
Deposit
Grade
Develop
Examine
10
The HOSDB Manual
Grade 0 Nothing visible
Grade 1
Grade 1
Grade 2
Grade 3
Grade 4
Grade 2
Grade 3
Grade 4

Identifiable

Borderline

Identifiable

Borderline
Not identifiable
Not identifiable
identifiable/
identifiable/
intelligence
intelligence
only
only

• A quick means of allowing a non-fingerprint
  expert to obtain a numerical value for quality
  based on area of developed ridge detail
• Subjective requires all grading by same person
• Can be analysed in several ways (average score,
  number of grade 3/4s, use of programmes such as
  Minitab)
• Can add secondary scores for aspects such as
  contrast, damage, background if required for
  experiment

11
The HOSDB Manual
Typical experiment looking at effectiveness of
brushes with aluminium powder
12
The HOSDB Manual

• Pseudo-Operational Trials

Used plastic bags and other non-porous articles
Fraudulently-passed bank cheques and used paper
13
The HOSDB Manual

• Believed to be the most comprehensively
  researched manual of its type used worldwide
• New techniques and equipment constantly being
  developed and requiring evaluation
• Changes in surfaces (e.g. recycled content in
  plastic bags) means effectiveness of techniques
  may change with time
• Changes in Health and Safety/environmental
  legislation may impose changes in formulations
• Work constantly being carried out to ensure
  advice in manual is current

14
Analysis of marks
15
Mark Y7

• Still visible on surface
• Apparently developed using a black powder
• Brush mark visible through mark

16
Mark Y7

• Evident that the door frame had been previously
  powdered using aluminium flake prior to
  application of black granular powder
• Deposition of aluminium more difficult to see and
  possibly less uniform than black granular powder

17
Mark Y7

• Was powdering the appropriate process to use?

18
Mark Y7

• Door frame could be regarded as a rough or
  smooth non-porous surface, in both cases
  processing charts indicate powdering as being
  appropriate for the circumstances not really
  any other option for fixed surfaces

19
Mark Y7

• Many types of powder and several methods of
  application are available for the development of
  latent fingerprints. With fresh fingerprints the
  aqueous component of the fingerprint contributes
  significantly to the adhesion of powders whereas
  with older fingerprints powders adhere
  principally to the fatty deposits of sebaceous
  sweat. The effectiveness of powdering is variable
  depending on the chemical and physical nature of
  the powder, the type of applicator and the care
  and expertise of the operator. Most available
  data indicate that under many circumstances the
  flake powders such as aluminium are more
  sensitive than other types of powder.
• PSDB Scene of Crime Handbook of Fingerprint
  Development Techniques, 1993

20
Mark Y7

• The sensitivity necessary in a powder to carry
  out an effective fingerprint examination depends
  to some extent on the nature and condition of the
  surface being examined.
• Use the powder most sensitive to the latent
  fingerprint deposit. Aluminium milled flake
  powder..(is) more sensitive, when applied in the
  manner described below, than other black or white
  powders.
• With deposits such as furniture polish or
  general grime a less sensitive powder may
  sometimes be more effective. This will reduce the
  chances of clogging, or filling in ridge detail.
• PSDB Scene of Crime Handbook of Fingerprint
  Development Techniques, 1993

21
Mark Y7

• Also need to take into consideration the
  experience and observations of SOCOs regarding
  effectiveness of powders in operational scenarios

22
Mark Y7

• Primary objective when treating a crime scene for
  fingerprint evidence must be to develop as many
  fingerprints as possible
• Choice of aluminium flake as initial powder not
  inconsistent with advice available in 1997
• Subsequent re-powdering with black granular
  powder after observations it may give better
  results on the painted wood surfaces at the locus
  also not inconsistent with advice available in
  1997
• Sequential powdering not bad practice, it may
  develop more marks overall however, no advice
  currently exists for optimum sequences
• Uncertainty arises because sequential powdering
  was not carried out immediately and Y7 was not
  developed by the initial aluminium flake powder

23
Mark Y7

• Why wasnt Y7 detected when powdering the door
  frame with aluminium flake powder?

24
Mark Y7

• The area containing Y7 was missed during
  powdering with aluminium
• The aluminium powder did not adhere well to the
  surface of the door frame in the vicinity of Y7
• Y7 was developed by aluminium, but not seen
  during subsequent examination of the door frame
• The constituents present in Y7 meant that it was
  not developed by aluminium flake, and that black
  granular powder was more appropriate for this
  type of mark
• Mark Y7 was deposited after aluminium flake
  powdering but before subsequent treatment with
  black granular powder

25
Mark Y7

• It has been observed in both pseudo-operational
  situations and also in experiments conducted
  during the course of the Inquiry that black
  granular powder can develop additional marks
  after initial powdering with aluminium flake
• This could have occurred for Y7, a brief
  experiment conducted during the Inquiry indicates
  5-10 marks may develop in this way

26
Mark Y7

• Powders have very different morphologies
• May also have very different adhesion mechanisms
  to fingerprints (e.g. flake favours wet marks,
  granular favours sticky marks) more research
  required to establish this
• This may account for why Y7 was not developed by
  aluminium but was by black granular powder
• However, there are other possible scenarios

27
Mark Y7

• If we can establish whether or not aluminium
  powder is present on the surface, and it is
  present whether it is above or below the
  fingerprint, we are better placed to comment on
  the likelihood of other scenarios
• Visual examination revealed patchy deposition of
  aluminium at top of door frame, no evidence of
  aluminium powder in immediate vicinity of Y7

28
Mark Y7

• Proposed use of Optical Coherence Tomography
  (OCT), sometimes described as optical
  ultrasound, to look at powder layers
• Uses reflections of infrared radiation from
  different materials and different layers in the
  surface to form an image
• Can produce depth profile images and slices
  through a material at different depths

29
Mark Y7

• Possible to distinguish between aluminium and
  black granular powders using OCT
• Aluminium seen as white specks on surface
• Black granular seen as dark specks on surface
  (large clumps) and as a shadow sub-surface

30
Mark Y7
Mark
OCT (surface)
OCT (sub-surface)
31
Mark Y7

• Cannot see any white specks associated with
  aluminium powder on surface in Y7, or in adjacent
  background region

32
Mark Y7

• Results suggest that either the region containing
  Y7 was missed during initial powdering, or that
  aluminium flake powder did not adhere to this
  region of the surface it is not possible to
  state which is the case
• Was not possible to scan a control region
  powdered with aluminium only on the door frame
  therefore results not fully conclusive
• Because aluminium is not obviously present, it is
  not possible to draw any conclusion about whether
  Y7 was deposited before or after the door frame
  was powdered with aluminium flake

33
Mark Y7

• Questions raised about unusual shape of mark Y7,
  in particular the presence of a step in the
  right hand side perimeter
• Different theories proposed to account for step
  feature
• Associated with multiple touches?
• Associated with a depression in the texture of
  the wood?
• Examination carried out to investigate whether
  texture of the wood could account for the step

34
Mark Y7

• Examination carried out under oblique lighting
  and specular lighting conditions
• Series of photographs taken to obtain information
  about wood texture and relationship of surface
  features with position of mark Y7

35
Mark Y7

• Oblique lighting can be used to exaggerate
  features on the surface
• Features present cast shadows which can be seen
  by an imaging system placed above the surface

36
Mark Y7
37
Mark Y7

• Specular lighting uses a light source the
  opposite side of the exhibit from the surface
• Disturbances in the reflected light due to
  surface texture can be captured by the imaging
  system

38
Mark Y7
39
Mark Y7

• Both oblique and specular lighting of the door
  frame confirm that there is a groove in the
  texture of the wood that runs alongside the right
  hand side of mark Y7
• This groove narrows and could account for the
  step feature seen in mark Y7

40
Mark QI2

• Not visible under normal lighting conditions
• Visible when illuminated using violet/blue light
  and viewed through yellow filters
• Developed using superglue, dyed with Basic Yellow
  40

41
Mark QI2

• Slight texture of screen printed design makes
  rough non-porous chart the most appropriate for
  processing of the metal tin
• Superglue one of the recommended options for this
  type of surface

42
Mark QI2

• Under fluorescence examination, pattern and
  colours of background make mark QI2 difficult to
  visualise
• Tin examined using ultraviolet imaging in an
  attempt to remove effect of patterned background
• Mark QI2 has previously been swabbed for DNA,
  flattening ridges and preventing mark being seen
  by this method

43
Mark QI2

• Why was mark QI2 printed as a blurred image when
  the negative is in focus?
• Intentionally to mislead a jury?
• To aid interpretation of ridge flow by an expert?

44
Mark QI2

• Ridge flow in red circled region easier to
  distinguish?

45
Mark QI2

• Blurring may have been carried out to aid
  interpretation of mark (analogous to squinting
  to see a pixellated image better)
• Adjustment of image at the printing stage not
  unusual for wet photographic processing (e.g.
  colour reversal, contrast enhancement, dodging
  and burning)
• Ideally, notes should have been made at the time
  of printing to describe if this was done and why
  it was done

46
Mark QI2

• Image adjustment more easy to perform on digital
  images
• Currently a requirement for digital fingerprint
  images presented in court in England and Wales to
  have an audit trail of what adjustments have
  been carried out
• This enables the image presented in court to be
  traced back to the original Master image

47
Mark QI2

• Enhancement tools including blurring and
  sharpening functions are available on all
  Automated Fingerprint Identification Systems as
  aid to expert interpretation of features prior to
  submitting marks for search
• In this case the enhancements used are not saved
  on the image
• If the image of QI2 was blurred to aid
  interpretation, this was not and is not unusual
• For digital images, audit trails should be kept
  of any such adjustments prior to submission to a
  fingerprint bureau

48
Mark XF

• Mark still visible on surface as white deposit,
  but now very faint
• Appearance of mark indicative of being developed
  using superglue, but tests carried out to examine
  possibility of development with white granular
  powder

49
Mark XF
White granular powder
Superglue

• Test marks on semi-porous, printed surfaces
• Marks developed using superglue appear crisper
  with no evidence of deposition on the background
  away from regions of contact
• Mark XF closely resembles marks developed using
  superglue, no evidence of powder on gift tag

50
Mark XF

• Was superglue to most appropriate process to use?
• Most interested in exterior surfaces of exhibit
• Need to decide whether to keep exhibit together,
  or split and treat each constituent part
  separately
• Have the following surfaces present
• Gift tag outer surface (semi-porous)
• Wrapping paper (semi-porous)
• Adhesive tape (non-porous)
• Soap bars (non-porous)

51
Mark XF

• Surfaces present are more likely to behave as
  non-porous materials than porous when treated
• Have demonstrated that superglue is probably
  better than powdering on semi-porous surfaces,
  therefore choice of superglue valid

52
Mark XF

• Could the mark have been planted?

53
Mark XF

• Various methods of planting or fingerprint
  forgery have been reviewed and discussed in the
  literature 1,2 including
• Deposition of a mark using a stamp, moulding,
  fake finger or photo-etched plate
• Transfer from one surface to another using a
  lifting medium
• Taken from fingerprints on arrest form using tape
  lifting or powdering then lifting
• Photo montage
• P A Wertheim, Detection of Forged and Fabricated
  Latent Prints, J. Forens. Ident., Vol 44(6),
  1994, p652-680
• B Geller et al, A Chronological Review of
  Fingerprint Forgery, J Forens. Sci., Vol 44(5),
  1999, p963-968

54
Mark XF

• Cannot be a photo montage
• Original exhibit is available for inspection and
  mark can be seen in situ on gift tag

55
Mark XF

• Does not appear to have been taken from arrest
  forms
• XF is wider in extent than arrest form plain
  impressions
• Ridges in XF are thicker than those on arrest
  forms and contain pores in some regions (none
  apparent on arrest forms)
• No evidence of paper fibres lifted from arrest
  forms or of powder on surface

56
Mark XF

• Could the mark have been transferred?

1)
3)
2)
4)
57
Mark XF
5)

• The transfer process results in some material
  being left behind on the surface, some being
  transferred to the lifting medium
• Each transfer operation results in less
  fingerprint residue being retained for subsequent
  development
• Mark XF is strongly developed, suggesting it is a
  primary natural deposit rather than a transferred
  mark

58
Mark XF

• Can produce realistic looking fingerprints from
  fake hands or mouldings by rubbing with natural
  sweat deposits or on forehead/side of nose and
  placing on surface
• Mark develops in normal way with appropriate
  development process
• Hard to tell from real fingerprint, but
  difficult to recreate fine detail, may contain
  mould defects, does not deform in the same way as
  a natural finger

59
Mark XF

• Magnified image of XF showing features indicative
  of natural origin
• yellow oval smearing of ridges due to movement
  of finger
• blue circle reproduction of ridges on tip of
  finger
• green circle pores visible within ridge
• red circle rings of fingerprint development
  around pores

60
Mark XF

• The features within mark XF are difficult
  (although not impossible) to create using a fake
  finger or moulding
• The ability to create such a moulding would rely
  on an accurate 3D cast being obtained from David
  Asbury prior to 13th January 1997 (when mark was
  first imaged)
• Based on all of the analyses above it is
  concluded that mark XF is a naturally deposited
  mark from a real finger