Chem 4630 Forensic chemistry 1

What this class will provide: - a toolbox of methods to analyze evidence - a perspective on how to analyze data - reinforcement of chemical and physical science methods

History of Forensic Science Mathieu J. B. Orfila: Many forensic science specialties can be traced back to the medicolegal institutes of Europe One of the most renowned medicolegalist of the time was Mathieu Orfila (1787-1853) Mathieu Orfila is best known for his involvement in the “Lafarge” arsenic poisoning case in France He is often referred to as the “father of forensic toxicology”

History of Forensic Science Hans Gross: A magistrate and law professor in Austria Known for his publications and for introducing the word “criminalistics” In 1893, published a Handbook for Magistrates that greatly influenced the practice of criminal investigations

History of Forensic Science Alphonse Bertillon: Developed an anthropometric system for human identification in the 1890s The limitations of this system was shown by its inability to distinguish between two Leavenworth, Kansas, penitentiary prisoners, Will West & William West The Bertillon system was eventually replaced by the fingerprint system being developed by Francis Galton, William Hershel, Edward Henry & others in the late 1800s

Development of Forensic Science Laboratories Professor R. A. Riess: Established a forensic photography laboratory at the University of Lausanne, Switzerland in 1909 Edmond Locard: Established one of the world’s first police crime laboratories in Lyon, France in 1910 Known for the Locard Exchange Principle

Development of Forensic Science Laboratories August Vollmer: Established a forensic laboratory at the Los Angeles Police Department in 1923 Colonel Calvin Goddard: Established a crime detection laboratory at Chicago’s Northwestern University in 1929 Perfected the comparison microscope for bullet and cartridge case examinations

Development of Forensic Science Laboratories J. Edgar Hoover: Established the Federal Bureau of Investigation (FBI) forensic laboratory in 1932 New York City (NYC): The NYC Police Department Crime laboratory was established in 1934

History of the Local Lab Most Crime Labs were established within police agencies and performed Firearms Fingerprints Photography Missouri State Highway Patrol Lab Established 1936 Full service lab system No questioned document examiners in Missouri labs

History of the Local Lab Formally known as SEMO Regional Crime Laboratory served the southeast Missouri region since 1969 Under direction of chemistry department First full time director in 1971 Prints, firearms, drug analysis serving 20 counties, 90 agencies Merged with MSHP in 2006

Forensic Science Specialties Four major areas of examination: Biological evidence Forensic Chemistry Pattern evidence Other patterns (scene reconstruction)

Forensic Science Specialties Forensic Pathology: Pathology is a specialty area of medicine Pathology is the study of diseases and the bodily changes caused by the diseases Forensic pathologists determine the cause of death (the medical reason why a person died; e.g. asphyxiation) Forensic pathologists determine the manner of death (the circum- stances causing death; e.g. homicide)

Forensic Science Specialties Forensic anthropologists: Can determine whether found remains are of human or animal origin Reconstruct the skeleton from found remains Provide an estimate of age, stature, and gender Can sometimes determine racial origin Detect skeletal abnormalities and any trauma Can provide information about the cause of death

Forensic Science Specialties Forensic Toxicology: Forensic toxicology is the study of the effects of extraneous materials such as poisons and drugs in the body Forensic toxicologists must determine both the presence and the amounts of extraneous materials in the body Assist the medical examiners in determining the cause of death May be involved in the determination of ethanol levels in blood and breath samples

Types of Uncertainty Error - the difference between the true value and our estimation Random Systematic Accuracy - the degree of agreement between the true value and the measured value Precision - a measure of the agreement of replicate measurements

Significant Figures and Scientific Notation Information-bearing digits or figures in a number are significant figures The measuring devise used determines the number of significant figures a measurement has The amount of uncertainty associated with a measurement is indicated by the number of digits or figures used to represent the information

Significant figures - all digits in a number representing data or results that are known with certainty plus one uncertain digit

Recognition of Significant Figures All nonzero digits are significant 7.314 has four significant digits The number of significant digits is independent of the position of the decimal point 73.14 also has four significant digits Zeros located between nonzero digits are significant 60.052 has five significant digits

Use of Zeros in Significant Figures Zeros at the end of a number (trailing zeros) are significant if the number contains a decimal point. 4.70 has three significant digits Trailing zeros are insignificant if the number does not contain a decimal point. 100 has one significant digit; 100. has three Zeros to the left of the first nonzero integer are not significant. 0.0032 has two significant digits

Determining Significant Figures How many significant figures are in the following? 3.400 3004 300. 0.003040

Scientific Notation Used to express very large or very small numbers easily and with the correct number of significant figures Represents a number as a power of ten Example: 4,300 = 4.3 x 1,000 = 4.3 x 103

Rules for Rounding Off Numbers When the number to be dropped is less than 5 the preceding number is not changed When the number to be dropped is 5 or larger, the preceding number is increased by one unit Round the following number to 3 significant figures: 3.34966 x 104 =3.35 x 104

How Many Significant Figures? Round off each number to 3 significant figures: 61.40 6.171 0.066494

Principles of modern forensic laboratories Comparison of evidence with known standards (Microtrace, DEA reference lib, FBI database) Disproving a null hypothesis Performing positive and negative controls on all tests