Scientific Method

Application to Criminalistics and Forensics

What is Forensics?

• Forensics is the application of science to the law that is enforced by local law enforcement.

• There two critical pieces that make up forensics (also known as criminalistics):– Crime Scene investigator: The people who interpret

what is and is not evidence at a crime scene, as well as putting together the puzzle of what happened.

– Laboratory technicians: The people who are the experts at analyzing evidence (prints, DNA, etc.)

The most common subjects

• Chemistry• Biology• Firearms/ballistics• Document

examination• Toxicology/drug

analysis

• Fingerprints• Odontology• Engineering• Geology• Entomology• Physics

Scientific method

• In science, as you all know, we use the scientific method to answer questions.

• What are the parts of the scientific method?• Make an observation• Form a hypothesis• Create/perform an experiment• Scientific Theory• Scientific Law

What does it look like in Forensics?

Observations ExperimentsTheory

Observations

Hypothesis

Experiments

Experiment

If hypothesis is false Make slight modifications

Collect evidence

Conclusion/final hypothesis

Collect evidence

There is a constant evolution of the original ideas based on the evidence found and the conclusions made.

Turn the case over to the judicial system

Wait for more evidence to appear

Making Observations: Facts vs. Perception

Perception is faulty! Brain Games

Eyewitness accounts

• Vary considerably from person to person– Prejudices, personal beliefs, motives

• Your brain fills in the details over time

• Our ability to observe is largely affected by our environment:– Weather, level of chaos, personal focus, etc.

• The innocence project found that 87% of wrongful convictions are due to incorrect eye witness accounts

In this class…

• Observations are CRITICAL!!• The rest is important too

• Here is what to expect on labs

Lab write-ups• Title

• Background information– Done before the labs

• Purpose

• Hypothesis

• Diagram– Pictures of apparatus used

with labels

• Procedure– Details, details, details.

• Data collection– Observations, data tables,

Calculations

• Presenting data and Graphs– Pictures of scene

• Conclusion– Analyze the data

Expectations on labs• Do your own work!• Organization and neatness counts

– If I can’t read it or find it then its worthless• Complete analysis of evidence

– Analyzing evidence is the point of this class• Thorough conclusions in complete

sentences– Prove to me you know what you are talking

about