Criminalistics: An Introduction to Forensic Science A drug can be defined as a natural or synthetic substance that is used to p

25 Mar Criminalistics: An Introduction to Forensic Science A drug can be defined as a natural or synthetic substance that is used to p

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Please find a forensics case that pertains to either chapter 11 or chapter 12

Criminalistics: An Introduction to Forensic Science

Twelfth Edition

Chapter 12

Drugs

Introduction (1 of 2)

A drug can be defined as a natural or synthetic substance that is used to produce physiological or psychological effects in humans or other higher order animals

Introduction (2 of 2)

The nature of the drug experience can be approached from two distinctly different aspects of human behavior:

Psychological dependence

Physical dependence

Psychological Dependence (1 of 4)

The common denominator that characterizes all types of repeated drug use is the creation of psychological dependence for continued use of the drug.

Psychological Dependence (2 of 4)

Emotional factors that play a part in drug dependence include the personal characteristics of the user, his or her expectations about the drug experience, society's attitudes and possible responses and the settings in which the drug is used.

Psychological Dependence (3 of 4)

The intensity of the psychological experience with drug is difficult to define.

Some drugs e.g., alcohol, heroin, and cocaine with continued use lead to a high degree of involvement.

Psychological Dependence (4 of 4)

Others such as marijuana and codeine have a lower potential for abuse.

Our general knowledge of alcohol consumption should warn us of the dangerous of generalizing when it come to drug abuse

Physical Dependence

Physical dependence is defined as the physiological need for a drug that has been brought about by its regular use. The desire to avoid withdrawal sickness, or abstinence syndrome, ultimately causes physical dependence or addiction.

Marijuana and cocaine are common drugs of abuse whose regular use does not lead to physical dependence.

Common Classification of Drugs of Abuse

Narcotics

Depressants

Stimulants

Hallucinogens

Narcotics (1 of 4)

Narcotic drugs are analgesics, meaning they relieve pain by a depressing action on the central nervous system. Their depressant effects impacts on blood pressure, pulse rate and breathing rate.

Narcotics (2 of 4)

The regular use of a narcotic drug will invariably lead to physical dependence.

The most common source for these narcotic drugs is opium, extracted from poppies.

Narcotics (3 of 4)

Morphine is readily extracted from opium and is used to synthesize heroin.

Addicts frequently dissolve heroin in water by heating it in a spoon, and then inject in the skin.

Narcotics (4 of 4)

Heroin produces a "high" that is accompanied by drowsiness and a sense of well-being that generally last for three to four hours.

Codeine is also present in opium, but it is usually prepared synthetically from morphine.

Synthetic Opiates Not Derived From Opium (1 of 2)

OxyContin, with the active ingredient oxycodone, is not derived from opium or morphine, but does have the same physiological effects on the body as do opium narcotics.

OxyContin is prescribed to a million patients for treatment of chronic pain.

Synthetic Opiates Not Derived From Opium (2 of 2)

Methadone is another well-known synthetic opiate.

Methadone, which is pharmacologically related to heroin, appears to eliminate the addict's desire for heroin while producing minimal side effects.

Depressants (1 of 4)

Depressants are substances used to depress the functions of the central nervous system.

Depressants calm irritability and anxiety and may induce sleep.

Depressants (2 of 4)

These include alcohol (ethanol), barbiturates, antianxiety drugs, and various substances that can be sniffed, such as airplane glue, model cement, or aerosol gas propellants such as freon.

Depressants (3 of 4)

Alcohol (ethyl alcohol) enters the body's bloodstream and quickly travels to the brain, where it acts to suppress the brain's control of thought processes and muscle coordination.

Barbiturates, or "downers," are normally taken orally and create a feeling of well-being, relax the body, and produce sleep.

Depressants (4 of 4)

Antianxiety drugs unlike barbiturates, produce a relaxing tranquility without impairment of high-thinking faculties or inducing sleep; e.g., Valium, Xanax.

Sniffing has immediate effects such as exhilaration, but impairs judgment and may cause liver, heart, and brain damage, or even death.

Stimulants (1 of 4)

The drug classification of stimulants includes amphetamines, sometimes known as "uppers" or "speed," and cocaine, which in its free-base form is known as crack.

Stimulants are substances taken to increase alertness or activity, followed by a decrease in fatigue and a loss of appetite.

Stimulants (2 of 4)

Amphetamine and methamphetamine, often injected intravenously, cause an initial "rush," followed by an intense feeling of pleasure.

This is followed by a period of exhaustion and a prolonged period of depression.

Stimulants (3 of 4)

Cocaine, extracted from the leaves of Erythroxylin coca, causes increased alertness and vigor, accompanied by the suppression of hunger, fatigue, and boredom.

Stimulants (4 of 4)

Crack is cocaine mixed with baking soda and water, then heated.

Crack is often smoked in glass pipes, and like cocaine, stimulates the brain's pleasure center.

Hallucinogens (1 of 2)

Another class of drugs is hallucinogens; marijuana is the most widely used illicit drug.

Hallucinogens cause marked changes in normal thought processes, perceptions, and moods.

Hallucinogens (2 of 2)

Marijuana is the most controversial drug in this class because its long-term effects on health are still largely unknown.

The Cannabis plant contains a chemical known as tetrahydrocannabinol, THC, which produces the psychoactive effects experienced by users. Its concentration various in the Cannabis plant.

Marijuana (1 of 3)

Marijuana refers to a preparation derived from the plant Cannabis.

The chemical substance largely responsible for the hallucinogenic properties of marijuana is known as tetrahydrocannabinol, or THC.

Marijuana (2 of 3)

The THC content of Cannabis varies in different parts of the plant, generally decreasing in the following sequence: resin, flowers, leaves, with little THC in the stem, roots or seeds.

Marijuana (3 of 3)

The THC-rich resin is known as hashish.

Marijuana does not cause physical dependency, but the risk of harm is in heavy, long-term use.

Other Hallucinogens (1 of 2)

Other hallucinogens include LSD, mescaline, PCP, psilocybin, and MDMA (Ecstasy).

LSD is synthesized from lysergic acid, and can cause hallucinations that can last for 12 hours.

Phencyclidine, or PCP, is often synthesized in clandestine laboratories and is often smoked, ingested, sniffed.

Other Hallucinogens (2 of 2)

Phencyclidine is often mixed with other drugs, such as LSD, or amphetamine, and is sold as a powder ("angel dust"), capsule, or tablet.

Oral intake of PCP first leads to feelings of strength and invulnerability, which may turn to depression, tendencies toward violence, and suicide.

Drug-Control Laws (1 of 2)

The U.S. federal law known as the Controlled Substances Act will serve to illustrate a legal drug-classification system created to prevent and control drug abuse.

Drug-Control Laws (2 of 2)

This federal law establishes five schedules of classification for controlled dangerous substances on the basis of a drug's:

potential for abuse

potential for physical and psychological dependence

medical value

Schedules of Classification (1 of 4)

Schedule I drugs have a high potential for abuse and have no currently accepted medical use such as heroin, marijuana, methaqualone, and LSD.

Schedule II drugs have a high potential for abuse and have medical use with severe restrictions such as cocaine, PCP, and most amphetamine and barbiturate prescriptions.

Schedules of Classification (2 of 4)

Schedule III drugs have less potential for abuse and a currently accepted medical use such as all barbiturate prescriptions not covered under Schedule II, such as codeine and anabolic steroids.

Schedules of Classification (3 of 4)

Schedule IV drugs have a low potential for abuse and have a current medical use such as darvon, phenobarbital, and some tranquilizers such as diazepam (valium) and chlordiazepoxide (librium).

Schedules of Classification (4 of 4)

Schedule V drugs must show low abuse potential and have medical use such as opiate drug mixtures that contain nonnarcotic medicinal ingredients.

Collection and Preservation (1 of 2)

The field investigator has the responsibility of ensuring that the evidence is properly packaged and labeled for the laboratory.

Generally common sense is the best guide, keeping in mind that the package must prevent the loss of the contents and/or cross-contamination.

Collection and Preservation (2 of 2)

Often the original container in which the drug was seized will suffice.

All packages must be marked with information that is sufficient to ensure identification by the officer in the future and establish the chain of custody.

Drug Identification (1 of 2)

The challenge or difficulty of forensic drug identification comes in selecting analytical procedures that will ensure a specific identification of a drug.

Drug Identification (2 of 2)

This plan, or scheme of analysis, is divided into two phases.

Screening test that is nonspecific and preliminary in nature to reduce the possibilities to a manageable number.

Confirmation test that is a single test that specifically identifies a substance.

Preliminary Analysis (1 of 4)

Faced with the prospect that the unknown substance may be any one of a thousand or more commonly encountered drugs, the analyst must employ screening tests to reduce these possibilities to a small and manageable number.

Preliminary Analysis (2 of 4)

This objective is often accomplished by subjecting the material to a series of color tests that will produce characteristic colors for the more commonly encountered illicit drugs:

Marquis Test – heroin and amphetamines

Duquenois-Levine – marijuana

Preliminary Analysis (3 of 4)

This objective is often accomplished by subjecting the material to a series of color tests that will produce characteristic colors for the more commonly encountered illicit drugs:

Scott Test – cocaine

Dillie-Koppanyi – barbiturates

Van Urk – LSD

Preliminary Analysis (4 of 4)

Microcrystalline tests can also be used to identify specific drug substances by studying the size and shape of crystals formed when the drug is mixed with specific reagents.

Confirmational Determination (1 of 2)

Once this preliminary analysis is completed, a confirmational determination is pursued.

Forensic chemists will employ a specific test to identify a drug substance to the exclusion of all other known chemical substances.

Confirmational Determination (2 of 2)

Typically infrared spectrophotometry or gas chromatography-mass spectrometry is used to specifically identify a drug substance.

Qualitative vs. Quantitative

Another consideration in selecting an analytical technique is the need for either a qualitative or a quantitative determination.

The former relates just to the identity of the material, whereas the latter requires the determination of the percent composition of the components of a mixture.

Chromatography (1 of 3)

Chromatography is a means of separating and tentatively identifying the components of a mixture.

The theory of chromatography is based on the observation that chemical substances have a tendency to partially escape into the surrounding environment when dissolved in a liquid or when absorbed on a solid surface.

Chromatography (2 of 3)

Henry's Law

When a volatile chemical is dissolved in a liquid phase and is brought to equilibrium with an air phase above it, there is a fixed ratio between the concentration of the volatile compound in air, and its concentration in liquid, and this ratio remains constant for a given temperature.

Chromatography (3 of 3)

In chromatography, one phase is always made to move in one direction over a stationary or fixed phase.

Those materials that have a preference for the moving phase will slowly pull ahead and separate from those substances that prefer to remain in the stationary phase.

In this illustration of chromatography, the molecules represented by the blue balls have a greater affinity for the upper phase and hence will be pushed along at a faster rate by the moving air. Eventually, the two sets of molecules will separate from each other, completing the chromatographic process.

Gas Chromatography (1 of 3)

In GC, the moving phase is actually a gas called the carrier gas, which flows through a column.

The stationary phase is a thin film of liquid contained within the column.

After a mixture has traversed the length of the column, it will emerge separated into its components.

Gas Chromatography (2 of 3)

The written record of this separation is called a chromatogram.

The time required for a component to emerge from a GC column is known as retention time.

Gas Chromatography (3 of 3)

In GC, the moving phase is actually a gas called the carrier gas, which flows through a column.

Basic gas chromatography.

Gas chromatography permits rapid separation of complex mixtures into individual compounds and allows identification and quantitative determination of each compound. As shown, a sample is introduced by a syringe (1) into a heated injection chamber (2). A constant stream of nitrogen gas (3) flows through the injector, carrying the sample into the column (4), which contains a thin film of liquid. The sample is separated in the column, and the carrier gas and separated components emerge from the column and enter the detector (5). Signals developed by the detector activate the recorder (6), which makes a permanent record of the separation by tracing a series of peaks on the chromatograph (7). The time of elution identifies the component present, and the peak area identifies the concentration.

FIGURE 12–11 (a) An unknown mixture of barbiturates is identified by comparing its retention times to (b), a known mixture of barbiturates.

TLC (1 of 2)

TLC uses a solid stationary phase usually coated onto a glass plate and a mobile liquid phase to separate the components of the mixture.

The liquid will slowly rise up the plate by capillary action causing the sample to become distributed between the stationary phase and the moving liquid phase.

TLC (2 of 2)

Because most compounds are colorless, the materials must be visualized by placing the plates under ultraviolet light or spraying the plate with a chemical reagent.

The distance a spot travels up a thin-layer plate can be assigned a numerical value known as the Rf value.

FIGURE 12–12

(a) In thin-layer chromatography, a liquid sample is spotted onto the granular surface of a gel-coated plate. (b) The plate is placed into a closed chamber that contains a liquid. As the liquid rises up the plate, the components of the sample distribute themselves between the coating and the moving liquid. The mixture is separated, with substances with a greater affinity for the moving liquid traveling up the plate at a faster speed.

Spectrohotometry

Just as a substance can absorb visible light to produce color, many of the invisible radiations of the electromagnetic spectrum are likewise absorbed.

Spectrophotometry, an important analytical tool, measures the quantity of radiation that a particular material absorbs as a function of wavelength and frequency.

The Spectrophotometer (1 of 3)

The spectrophotometer is the instrument used to measure and record the absorption spectrum of a chemical substance.

The Spectrophotometer (2 of 3)

The components of a spectrophotometer are:

A radiation source

A monochromator or frequency selector

A sample holder

A detector to convert electromagnetic radiation into an electrical signal

A recorder to produce a record of the signal

The Spectrophotometer (3 of 3)

Absorption spectra can be done in the visible, ultraviolet (UV) or infrared (IR) regions.

The parts of a simple spectrophotometer.

UVand IR Spectrophotometry (1 of 2)

Currently, most forensic laboratories use UV and IR spectrophotometers to characterize chemical compounds.

The simplicity of the UV spectrum facilitates its use as a tool for determining a material's probable identity, although it may not provide a definitive result.

UVand IR Spectrophotometry (2 of 2)

The IR spectrum provides a far more complex pattern.

Different materials always have distinctively different infrared spectra; each IR spectrum is therefore equivalent to a "fingerprint" of that substance.

FIGURE 12–16 The ultraviolet spectrum of heroin.

FIGURE 12–17 The ultraviolet spectrum of amphetamine.

Mass Spectrometry (1 of 2)

In the mass spectrometer, a beam of high-energy electrons collide with a material, producing positively charged ions.

These positive ions almost instantaneously decompose into numerous fragments, which are separated according to their masses.

Mass Spectrometry (2 of 2)

The unique feature of mass spectrometry is that under carefully controlled conditions, no two substances produce the same fragmentation pattern.

FIGURE 12–20 (a) Mass spectrum of heroin. (b) Mass spectrum of cocaine.

FIGURE 12–21

A tabletop mass spectrometer. (1) The sample is injected into a heated inlet port, and a carrier gas sweeps it into the column. (2) The GC column separates the mixture into its components. (3) In the ion source, a filament wire emits electrons that strike the sample molecules, causing them to fragment as they leave the GC column. (4) The quadrupole, consisting of four rods, separates the fragments according to their mass. (5) The detector counts the fragments passing through the quadrupole. The signal is small and must be amplified. (6) The data system is responsible for total control of the entire GC/MS system. It detects and measures the abundance of each fragment and displays the mass spectrum. Source: © Agilent Technologies, Inc. 2013 Reproduced with permission, courtesy of Agilent Technologies, Inc.

GC and Mass Spectrometry (1 of 3)

A direct connection between the GC column and the mass spectrometer allows each component to flow into the mass spectrometer as it emerges from the GC.

The separation of a mixture's components is first accomplished by the GC.

GC and Mass Spectrometry (2 of 3)

Then, fragmentation of each component by high-energy electrons in the mass spectrometer, will produce a distinct pattern, somewhat like a "fingerprint", of the substance being examined.

GC and Mass Spectrometry (3 of 3)

A direct connection between the GC column and the mass spectrometer allows each component to flow into the mass spectrometer as it emerges from the GC.

FIGURE 12–19 How GC/MS works. Left to right, the sample is separated into its components by the gas chromatograph, and then the components are ionized and identified by characteristic fragmentation patterns of the spectra produced by the mass spectrometer.

Criminalistics: An Introduction to Forensic Science

Twelfth Edition

Chapter 11

Hairs and Fibers

Introduction (1 of 2)

Hair is encountered as physical evidence in a wide variety of crimes.

It is not yet possible to individualize a human hair to any single head or body through its morphology; however, partial success for individualizing human hairs has been achieved by isolating and characterizing the DNA present in hair.

Introduction (2 of 2)

When properly collected and submitted to the laboratory accompanied by an adequate number of standard/reference samples, hair can provide strong corroborative evidence for placing an individual at a crime scene.

Morphology of Hair (1 of 2)</p

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25 Mar Criminalistics: An Introduction to Forensic Science A drug can be defined as a natural or synthetic substance that is used to p

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