Criminalistics: An Introduction to Forensic Science

These flashcards cover key concepts from a forensic science lecture, focusing on methods of evidence analysis, types of evidence, and biological mechanisms related to criminalistics.

What are trace elements and why are they important in forensic science?

Trace elements are small quantities of elements present in concentrations of less than 1%, used as 'invisible' markers to establish the source of a material or for points of comparison.

How does an emission spectrograph work?

An emission spectrograph vaporizes and heats samples to create excited atoms that emit light, which can be analyzed for line spectra to identify elements.

What are the energy levels in an atom?

Energy levels are associated with a definite amount of energy, and each element has its own set of characteristic energy levels.

What happens when electrons in an atom absorb energy?

Electrons are pushed into higher energy level orbitals, which makes the atom enter an excited state.

What is inductively coupled plasma (ICP) emission spectrometry?

ICP is a technique where samples in aerosol form are introduced into a hot plasma to create charged particles that emit light corresponding to the elements present.

What is neutron activation in forensic chemistry?

Neutron activation involves bombarding atoms with neutrons to produce radioactive isotopes for identification and quantification of elements.

What is the importance of paint in forensic science?

Paint can serve as physical evidence in crimes, commonly found in hit-and-run and burglary cases, through its unique composition and color.

What techniques are used for paint comparison?

Techniques include visual comparison under a microscope, pyrolysis gas chromatography, and infrared spectrophotometry.

What procedures are followed for soil evidence collection?

Collect standard/reference soils at various intervals and avoid removing soil from suspects; package each soil sample separately.

What is the purpose of blood typing?

Blood typing identifies blood types using antigens and antibodies, critical for forensic examinations and establishing relationships.

How is the precipitin test used in blood origin testing?

The precipitin test determines if a blood stain is of human or animal origin using antisera derived from injected animal blood.

What role do STRs play in DNA profiling?

Short Tandem Repeats (STRs) are sequences of DNA that repeat; they are key to individual identification in forensic DNA analysis.

What is the function of DNA polymerase in PCR?

DNA polymerase is an enzyme that synthesizes new DNA strands during the polymerase chain reaction process.

How does amplification using PCR benefit forensic analysis?

PCR can produce millions of copies of small or degraded DNA samples, making it easier to analyze them.

What is the combined DNA Index System (CODIS)?

CODIS is a software program developed by the FBI to maintain databases of DNA profiles from convicted offenders and crime scene evidence.

What is mitochondrial DNA, and how is it different from nuclear DNA?

Mitochondrial DNA is inherited from the mother and located outside the nucleus, while nuclear DNA is found within the nucleus and provides more discrimination power.

How are biological evidence items packaged for forensic analysis?

Biological evidence should be packaged in breathable containers, each item separately, to prevent contamination and preserve the sample.