Lessons learned

from 

“A Life in Crime”

Sheila Willis

Points of view in this document are those of the author and do not necessarily represent the official position

or policies of the National Institute of Standards and Technology. Certain commercial entities are identified in order to specify

experimental procedures as completely as possible. In no case does such identification imply a recommendation or

endorsement by the National Institute of Standards and Technology nor does it imply that any of the entities identified are

necessarily the best available for the purpose. 
Population 4.67m

32,595 sq miles
So you are a 

scientist?

So what does 

a forensic 

scientist do? Predates the time of alphabet soup

idscna
Problem was the scene

Measured effluent across the paper mill

Expected lot of variation across the 

factory

Found quite reproducible results

Wet water chemistry 
Complexity of the scene

Weapon 

blood 

stained

Victim?
Main evidence 

matching green 

paints

Murder of Lord 

Louis Mountbatten 

and others
Court Experience

• Factual report; emphasis in report on technical details;

• Green paint – white paint – lots of paint

• Interest from the bench about the activity – didn’t 

recognize this at the time;

• Black jacket”

Political changes

Political issues in 

forensic science 

also

Intimidation

Trauma of human court

Last Drugs case

Need for solid science –

not enough 

3 types of witnesses


SOPs become too rigid

Everyone becomes too reliant on the value of the protocols 

and ignores judgement

Tasks are carried out to comply with the system rather than 

answer relevant questions

Personal responsibility/ownership abdicated to the system

Quality system

Frame work for 

continuous 

improvement

Can be 

mistaken as 

guarantee for 

correct result 

Accreditation
Personal Experience

• Documentation becomes overly complicated

• Staff develop perceptions of what is in documentation

• Rigid adherence to protocols when judgement requires 

different approach

• Sticking plaster approach v root cause 

Journal article

Value of accreditation taken 

for granted Not enough 

scientific skepticism in 

use Not enough emphasis on 

“Why”

Performance identified
Straightjacket or lifebelt
Principles rather than rule based approach
Learn from History?

• Forensic Science doesn’t have a good record in 

transferring learning from generation to 

generation or from discipline to discipline

• Orfilia – toxicology – contamination – leeching of 

arsenic from soil

• Fiber work in FSL - consider methods of 

contamination avoidance

• Visited laboratories with all work on one bench

• Digital – manage information – relevance now the 

issue as with all other information

• Lack of underlying principles the issue

• Each new area considers the forensic issues as 

new to them
Paul Kirk

"Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will 

serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, 

the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he 

scratches, the blood or semen he deposits or collects. All of these and more, bear mute 

witness against him. This is evidence that does not forget. It is not confused by the 

excitement of the moment. It is not absent because human witnesses are. It is factual 

evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly 

absent. Only its interpretation can err. Only human failure to find it, study and understand 

it, can diminish its value." (8) So the physical objects preserved and the microscopic images 

or analytical maps of real physical evidence recorded are the heart and soul of forensic 

science, because they, themselves, do not lie.

"There exists in the field of criminalistics, a serious deficiency in basic 

theory and principles , as contrasted with a large assortment of effective 

technical procedures."

The ontogeny of criminalistics by Paul Kirk 1963
Mis Information
Based on Case assessment and Interpretation

Standards Association of Forensic Science Providers 

Cook, R., Evett, I. W., Jackson, 

G., Jones, P. J. and Lambert, J. 

A. 'A model for case 

assessment and 

interpretation', Science and 

Justice, 38(3), pp. 151-156.

Standards for the formulation 

of evaluative forensic science 

expert opinion ; Science and 

Justice 49 (2009) 161–164 
Case 

Assessment & 

Interpretation

• Fixed situations where two items questioned 

and known are tested for comparison

• If any transfer is involved, need information 

over and above the physical or chemical 

properties of the items in question – need 

information on how likely are they to transfer 

and be detected to populate the numerator 

and how many other people in the population 

(however that population is defined) are likely 

to have such material to populate the 

denominator – activity information

• Smears in traffic accidents

• Multiple fragments in glass

• Types that shed in fibers

• DNA findings led?

• Changing – increasing number of reviews on 

transfer issues

What to Expect

van Oorschot, R. A. H., Szkuta, B., Meakin, G. E., 

Kokshoorn, B. and Goray, M. (2018) 'DNA transfer 

in forensic science: a review', Forensic Science 

International: Genetics 38 (2019) 140–166 

.

.
Practical 

example 

from my 

work this 

year

• DNA - the holy grail

• So successful that it is pushed to the 

absolute limit –

• Consistent narrative ignored

• If measurement is taken out of context or 

becomes the total focus, we risk having a 

different type of problem

• Are we satisfied that a genotype taken 

from a complex mixture in a one off 

situation with no option of retesting is 

suited to the criminal justice system?

• The reality today is that the total focus on 

how we get a number from such a situation 

may completely miss the uncertainty issues 

which in turn have the potential to 

undermine the LR at source or sub-source 

level
Extensive blood 

stains

DNA profile 

matching victim

Mixed 

profile

Some 

association 

with POI

Information that hammer used in attack

Is it reasonable to suggest that we cannot have 

the same confidence in DNA from each situation?

Should we consider alternative propositions?
Aim for 

simplicity

• Locard “every contact leaves a trace” defines forensic 

science and is used outside the field.

• The actual translation from Locard “The truth is that 

none can act with the intensity induced by criminal 

activities without leaving multiple traces of his path---” 

gives us more insight. It has been explained (Roux et al., 

2015) to be composed of three parts

• “Nature of the criminal activity influences the types of 

material that are exchanged, and how they are 

dispersed in the environment

• These materials, remnants of the activity, are the traces 

that become signs when detected, recognized, 

collected and measured

• The interpretation process aims at transforming them 

into clues in order to reconstruct what occurred” 

The implication of this is that more thought is needed 

about what to expect in given situations which is what we 

undertake when considering activity propositions

Also need to be conscious of what’s missing
R. v. Anne Maguire, Patrick Joseph Maguire, William 

John Smyth, Vincent Maguire, Patrick Joseph Paul 

Maguire, Patrick O'Neill and Patrick Conlon (1991) 

94 Crim. App. R. 13
’A’ secretor status

Mixed stain – victim and suspect

Reaction only to be expected if from semen

Disagree - colleagues

Never asked – not disclosed

Review -“In many ways Dr Clift’s attitudes 

reflect those of the very early forensic scientists 

who saw their function as one of ‘helping the 

police’ and not as I believe a modern forensic 

scientist would see it (a) to assist police in their 

investigations and (b) to assist in the cause of 

justice in the courts. “Mick Hamer, ‘How a 

forensic scientist fell foul of the law’, New 

Scientist, 3 September 1981, pp. 575–6.

What to disclose
Type of 

reports

Technical 

reports

Investigative reports Evaluative reports Intelligence 

reports

Characteristic Factual Explanations Comparisons Linking series

Use Often legal 

definition

Leads during investigation 

or explanations for 

findings

Comparing 

questioned and 

known samples or 

evaluate findings in 

light of competing 

propositions

Collating findings 

to provide data for 

evidence based 

policing

Examples Level of 

active 

ingredient 

in a white 

powder;

Level of 

alcohol

Explanation for blood 

pattern at a scene;

“ observations made on 

the cartridge case suggest 

that it has been fired by 

an ASTRA 9mm pistol.” 

Comparison of DNA 

profiles;

Glass fragments;

Kicking versus walk 

by;

Patterns of 

fingerprints or 

footprints at 

scenes linked with 

various types of 

other findings –

DNA, Partial marks

Tools/mechanism Error rates, 

SD

Narrative Likelihood ratio at 

source or activity 

Computer 

programs
Lessons learned from 

a ’Life in Crime’

1. Forensic science as a discipline is not recognized partly because it is not well 

defined and means different things to different people and therefore progress is 

difficult

2. The lack of a common language works against progress, as does an agreed 

shared understanding of a common knowledge base

3. A lack of articulation and acceptance of principles prevents learning transferring 

from one generation to the next and from one discipline to another

4. There is not enough emphasis on the scene and how to communicate to the 

court

5. Accreditation is a valuable management tool but needs to be seen as 

continuous improvement and not used to stifle scientific curiosity

6. Education is key to progress and a strong code of ethics is needed across the 

field of forensic science 

7. Leadership needed in the field – lot of noise from the outside

8. Blind acceptance or complete rejection of test methods is not helpful when the 

contribution is dependent on the question asked 

9. Paradoxically the demand for more service is reducing the contribution from the 

service – more test results not always more answers

10. Need a system where science supports justice
Thank you very much for your 

attention