Chapter 6: Inorganic Analysis

Inorganic Evidence Inorganic compounds do not contain carbon. Carbon Dioxide is an exception Earth’s most abundant elements do not include carbon. ¾ of the Earth’s crust is composed of Oxygen and Silicon

Inorganic Evidence Oxygen is found in water, carbon dioxide, and many organic compounds. Silicon is commonly found in dusts, sands, silicon dioxide, and silicates. Silicates include cement and thousands of minerals. Quartz crystal

Identification and Comparison of Physical Evidence Forensics requests include the analysis of explosives containing potassium chlorate poisonous powders containing arsenic Chemical compositions/formulations vary. Potassium chlorate Potassium nitrate

Trace Elements Impurities exist in the raw materials obtained from the Earth’s crust. May be removed through industrial processes Often not done Do not affect appearance or performance of a product. Present in concentrations less than 1% Trace elements provide “invisible” markers that may establish the source of a material

Trace Elements Matching two brass pipes to a crime scene Brass is a combination of copper and zinc. A comparative analysis of the percent of copper and zinc may not be 100% conclusive. Matching percents of trace elements provides a conclusive analysis to the origins of the brass pipes.

Analysis of Materials Evidence can also be analyzed through other characteristics. Cross sections of metals and other objects can identify their origins. Composition, manufacturing processes

JFK Assassination Forensic investigators investigate trace elements present in soil, fibers, glass, and metals. Forensics was used to investigate the death of President John F. Kennedy.

Timeline of JFK’s Death President Kennedy was killed Nov 22, 1963 Warren Commission reconstructed the crime… 1. Suspect Lee Harvey Oswald fired three shots from an Italian Carcano carbine military rifle. 2. Oswald positioned behind President’s motorcade in Texas School Book Depository Building. 3. Two bullets struck President Kennedy, 1 missed

Timeline of JFK’s Death 4. One bullet struck Kennedy in the back – exited through his throat. 5. Same bullet struck Governor Connally in his back near his right armpit – exited his chest, struck his right wrist, and lodged in his left thigh. 6. Third bullet fired struck President Kennedy in the skull and killed him.

Facts about the JFK Assassination Review of events leading up to the assassination of President Kennedy. Plausible Conspiracy Theories?

The Kennedy Assassination: Beyond Conspiracy Complete the Question Set as you watch the video. http://www.youtube.com/watch?v=Qi14A20MJbE

Can a Single Gunman Fire 3 Accurate Shots? http://www.youtube.com/watch?v=WovyEqfR8Hg https://www.youtube.com/watch?v=qSWSgcuYqDo

JFK Assassination Forensic Analysis of the “Magic Bullet” Theory. http://www.youtube.com/watch?v=DSBXW1-VGmM

Analysis of the Kennedy AssassinationBullets Antimony and silver concentrations are consistent in bullets/fragments recovered from… * Measured in PPM (parts per million) Governor Connally President Kennedy’s skull

Ballistics Evidence Bullet Deformation occurs due to impact forces acting against the momentum of the bullet. Factors that affect the percent of deformation include Initial velocity of bullet Density of object being struck Loss of bullet velocity after first impact Angle of impact

Ballistics Evidence Why did the “Magic Bullet” show very little deformation after striking both President Kennedy and Governor Connally?

Emission Spectrum of Elements Emission spectrum – light emitted from a source and passed through a prism Separated into its components or frequencies Continuous spectrum – all color blend into a single band Line spectrum – colors show as single colored lines Separated by black areas

Carbon Arc Emission Spectrometry Obtains and records the line spectra of elements. 1. Heat vaporizes and excites atoms of a specimen. 2. Light collected by a lens. 3. Focused on a prism. 4. Separated frequencies recorded on photo plate.

Identifying Class Evidence Bullets and Glass fragments Paint, plastics Compositional differences in trace elements Lead-based bullets contain… Copper, arsenic, silver, antimony, and cadmium Individual evidence can be presented in a court of law

Atomic Structure Elements are collections of atoms all having the same number of protons. Electron orbitals have a definite amount of energy Due to number / set path of electrons Excited State – movement of electrons to higher levels when heat/light absorbed Emission of light causes electrons to drop back to lower energy level.

Neutron Activation Analysis Radioactivity – emission of radiation from unstable nuclei of some isotopes Three types pf radiation Alpha Particles – composed of He atoms Beta Particles – consists of electrons Gamma Rays – high-energy electromagnetic radiation

Neutron Activation Analysis Advantage – nondestructive method for identifying and quantitating trace elements Disadvantage – very expensive and regulated Requires a nuclear reactor

Neutron Activation Analysis 1. Bombard sample with neutrons 2. Neutrons react with nucleus of an atom 3. Sample will decay into another type of atom Different elements are identified as they decay

X-Ray Diffraction Explains how elements are combined into compounds. Diffraction Patterns – series of light and dark bands Only used with solid crystalline materials Applies to 95% of inorganic compounds

The Son of Sam Case Study Berkowitz Part I http://www.youtube.com/watch?v=m5DVFvOg41A Berkowitz Part II http://www.youtube.com/watch?v=g4I24bcWfRg

The Son of Sam Case Study Part III http://www.youtube.com/watch?v=LLICwdYAUX8 Part IV http://www.youtube.com/watch?v=Eu1SpnckxjA

The Son of Sam Case Study Part V http://www.youtube.com/watch?v=P4pGdRIQLsE

Son of Sam Forensics Did David Berkowitz Act Alone? Part I http://www.youtube.com/watch?v=dWye42jcoWM Part II http://www.youtube.com/watch?v=VdLV_T4H5Bs