Chapter 6: Inorganic Analysis

Inorganic Evidence Inorganic compounds do not contain carbon. Carbon Dioxide is an exception 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 explosives containing potassium chlorate poisonous powders containing arsenic poisonous powders containing arsenic Chemical compositions/formulations vary. 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 May be removed through industrial processes Often not done Often not done Do not affect appearance or performance of a product. 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 of trace elements provides a provides a conclusive analysis conclusive analysis to the origins of the to the origins of the brass pipes. 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 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.

Ballistics Evidence occurs due to impact forces acting against the momentum of the bullet. 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 Initial velocity of bullet Density of object being struck Density of object being struck Loss of bullet velocity Loss of bullet velocity after first impact Angle of impact Angle of impact Composition of bullet Composition of bullet

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

Radioactivity Radioactivity – emission of radiation from unstable nuclei of some isotopes Three types of radiation Alpha Particles – He atoms Beta Particles – electrons Gamma Rays – HE electromagnetic radiation

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 Different elements are identified as they decay

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

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 Applies to 95% of inorganic compounds