Hair Analysis

19 04 2010

Q

An intentional murder has occurred. The victim was stabbed several times. The culprit has not yet been discovered. There are three suspects that the investigators are suspicious of. They were confused between the three. Then, a strand of hair was discovered on the ground. They immediately got the warrant to get all suspects’ hair. What should one do as a forensic scientist?

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A

One should carry out a comparative analysis using the comparison microscope to compare the unknown hair and the suspects’ hairs.

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Hair is the outgrowth of filamentous cells containing keratins from the follicles. A strand of hair can tell us a lot about the identity of the culprit. This is the structure of a strand of hair.

What distinguishes human hair from other species are the cuticle and medulla.

Two light sources can be used to examine a strand of hair: direct and oblique. Direct lighting is lighting from underneath. It shows the inner structures of the hair. Oblique lighting is lighting from the side. It highlights the cuticle of the hair.

Hair can have three scale patterns.

  1. Coronal
  2. Spinous
  3. Imbricate

1. Coronal
Coronal pattern has scales that look like stacked crowns or paper cups. An example is a bat’s hair.

2. Spinous
Spinous scale pattern has petal-shaped scales, protruding from the hair surface. The example of a spinous pattern is rabbit hair.

3. Imbricate
The scales of imbricate pattern are flattened to lie closer. Humans and dogs have this pattern.

There are three types of medulla.

  1. Continous
  2. Interrupted
  3. Fragmented/Absent

1. Continous
A continous medulla is the medulla formed in the center of the hair as a solid line. An example is the dog’s hair.

2. Interrupted
The medulla is seen as individual cells, as if it is fragmented. The pattern can be regular or irregular. The rabbits have this type of medulla.

3. Fragmented/Absent
There is almost no medulla in the hair. This is a characteristic of a human hair.

The follicular tag tells whether there is a nuclear DNA or not.  The follicular tag surrounds the root, which is the site of hair growth. It supplies the hair with nutrients. When hair is pulled out, the follicular tag is sometimes removed. Even if there is none, we can still test for mtDNA, or mitochondial DNA.

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Toxicology

5 04 2010

Q

There was a car accident. A car crashed into another car. The man who crashed into another car was a good man. He was a dilligent worker and a good father. The investigators want to know why the man did such thing. They are wondering if the man was drunk or on drugs. What should they do to find out if the man was drunk or on drugs?

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A

They should ask the toxicologist to analyze by doing head gas chromatography, elisa test, and gas chromatograph/mass spectrometer. Doing head gas chromatography will reveal the presence of alcohol, and elisa test and GC/MS will reveal the presence and the type of drugs.

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In the 16th century, Paracelsus realized that anything can kill a human if it is taken excessively. But forensic toxicology wasn’t invented until the 1840s. A chemist named Mathieu Orlifa proved in court that Marie LaFarge poisoned her husband with arsenic.

Toxicology is science concerned with nature, effects, and detection of poisons.Forensic toxicologists test human fluids and tissues to determine the presence of drugs and other chemical substances.

In order to carry out the test, toxicologists draw out 3 types of bodily fluids

  1. 2mL of vitreous humor
  2. 30mL of blood
  3. 30mL of urine

1. 2mL of virtreous humor

Virtreous humor is the clear fluid inside the eye that give the eye its shape. It is inside your eye balls! Virteous humor is used as a confirmation to confirm the results from the blood and urine, because if a drug is present in any of these fluids, it will be present in all three. The vitreous humor is collected using a syringe. The toxicologist pokes the syringe through the eye ball and extracts the fluid inside. I won’t upload a video, because it is a quite disgusting process to see 😦

2. 30mL of blood

Blood transports oxygen, nutrients, and other chemicals throughout a person’s body. Hemoglobin is a well known protein in blood that transports oxygen. Most chemicals in the body will appear in a person’s blood stream. Once the drug enters the blood stream, it will spread all throughout the body.

3. 30mL of urine

Urine is the main way toxins and other chemicals exit the body. The toxicologist collects the urine postmortem from the bladder, again, using a syringe.

So why are three fluids examined? It is because looking at multiple fluids helps prevent error and contamination. If a drug is present in one part of the body, it should also be in others.

These are the sccening tests driven to determine the presence of alcohol/drugs.

  1. Headspace Gas Chromatography
  2. Elisa Test
  3. Gas Chromatograph/Mass Spectrometer

1. Headspace gas chromatography

Headspace gas chromatography is used to refer to the area between the sample and the top of the vial. The alcohol in the sample will evaporate into the headspace, where it can be analyzed.

2. Elisa Test

Elisa test is used to detect drugs in the sample. It can detect the presence of drugs, but it cannot definitely identify individual chemicals. All samples and controls are replicated twice the make sure no mistakes are made. The samples change color when a drug is detected. Positive and negative controls are used to ensure that the test is working correctly. The positive control purposefully have drugs, and the negative control doesn’t.

3. Gas chromatograph/Mass spectrometer

To find out the exact drug, gas chromatoraph/mass spectrometer, or GC/MS is used. It is only used if something shows up in the screening tests, because this is a very expensive test :(. GC/MS separates the chemicals in a specimen and identifies each one. It takes up to 20 minutes for the processing to complete. The chemicals in the sample separate from each other based on their properties. Then, the chemical gets a positive change in the ion source, and breaks into fragments. The analyzer sorts the fragments, again, by similar properties. The detector calculates the number of chemical fragments of each type. A graph is generated for each chemical. The graph is called mass spectrum. The chemicals broken into fragments are indicated as the peaks on the graph. Every chemical has its own unique pattern. The presence of drug is found by comparing the graph to other graphs of samples with different types of drug intake.





Medical Examination

28 03 2010

Q

A teenager was found dead one day. The parents have no idea why their child is dead. They want to find out the cause of death and the manner of death. What should they do?

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A

They should request medical examination. External and internal autopsies will be done to figure out the cause and the manner of death.

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Medical Examination is the first thing done when the corpse arrives in the laboratory. The first thing the medical examiner does is an external autopsy; they look for clues on the outside of the body. This is done, because in most cases, what can be found on the outside can be more helpful than what can be found on the inside. Then, internal autopsy is done. The examiner looks at the internal organs to find out if he/she had a disease or damage. Many years of training in medical school must be done to become a forensic pathologist, as I said on a post that I wrote before.

First, before you start any autopsy process, you need to put on protective materials, such as gloves, eye protection, surgical clothes, etc.

Autopsy is a very complicated process, that requires a good stomach. You will be able to find a good amount of disgusting pictures if you type “forensic autopsy” on google! The autopsy always begins with a Y-incision. Next, you will remove the rib cage and expose the inner organs. You will use the rib cutter to do so. Then, you will extract some blood to use as samples for the toxicology lab.  You will poke the syringe through the heart for extraction. You will then use a technique called Rokitansky’s technique. All organs will be removed together and further dissected outside the body. Scalpel will be used to carry out this process. Then, you will need to observe the brain for signs of trauma. You will first have to expose the skull. Stryker saw will be used. Now, all necessary organs are removed. They can be now studied individually in more detail. You will weigh all organs and cut them open. Observing the organs will lead you to figure out what the cause of death is. After you figure out the cause of death, you will also have to figure out the manner of death. Manner of death is what describes how the cause of death occurred.

There are five choices

  1. Natural
  2. Homicide
  3. Suicide
  4. Accidental
  5. Undetermined

1. Natural

Natural death is sudden or unexpected death cause by disease, usually by heart disease, brain system disorder, and nervous system disorders. It can occur at any age. It is seen in 38% of cases

2. Homicide

It is death caused by another person, intentionally or accidentally. If it was accidental, it is not considered a murder. It is determined by the court. It is seen in 9% of cases.

3. Suicide

Suicide is self-caused death. Usually, suicide committers have psychological problems. It is seen in 9% of cases.

4. Accidental

Accidental death is the most common manner of death. It is used if death was unintentional or unavoidable. It is seen in 40% of cases.

5. Undetermined

Undetermined deaths are deaths that do not have certain circumstances surrounding. This is usually temporary classification until the investigation is complete. It is see in 4% of cases as their final decision.

Even before medical examination, the body can tell us many things about when someone died.

  1. Algor Mortis
  2. Rigor Mortis
  3. Livor Mortis

1. Algor Mortis

Algor mortis is the body temperature. After death, the body cools down at a certain rate until it reaches the surrounding temperature. We insert the thermometer into the liver to accurately measure the internal body temperature.

2. Rigor Mortis

Rigor mortis is the stiffening of the muscles. As time passes, the body will become stiff. Later, It will become so stiff that it won’t be able to be moved

3. Livor Mortis

Livor mortis is the discoloration of the body. Lower areas will turn dark blue or purple, because that is where the blood settles.





Firearms

25 03 2010

Q

An innocent citizen has been shot while he was on a walk. Two bullets have been shot towards him. The investigators gained the bullets that were pulled out of his body after death. The citizen is badly hurt, but has a very poor family. He has this weird insurance where he needs to find the shooter in order to get the money. How are the investigators supposed to find the criminal for this case?

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A

Firearm examiners can match a bullet to a specific gun. The bullets can be given to them to study.

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Firearm means portable gun. Firearm examiners can match a bullet to a specific gun by looking at the shape of the bullet that has been shot.

This gun is semiautomatic hand gun. It fires a single cartridge.

To shoot…

1.Trigger has to be pulled

2. The hammer is triggered to hit the firing point

3. The firing pin hits cartridge, releasing the bullet.

This is a picture of the cartridge and its parts.

There are a few characteristics of bullets that can be used to distinguish them. There are class characteristics, specific for a certain brand or type of firearm, and individual characteristics, specific for an individual fire.

Class characteristics

  1. Conventional rifling
  2. Polygonal rifling

1. Conventional rifling

Conventional rifling is a traditional rifling technique that makes deep, easily visible grooves on the surface of the bullet.

2.Polygonal rifling

Polygonal rifling is a technique that leaves smooth rifling impressions, that can be really har

Individual characteristics

  1. Rifling number
  2. Rifling direction
  3. Striations

1. Rifling number

Rifling number is the number of grooves in the rifled barrel. The rifling number can be determined by rotating the bullet and counting the number of the grooves left on the surface.

2. Rifling direction

Rifling grooves are spiral either to left or right, or right or left, making the spin clockwise or counterclockwise int he air when the bullet is floating in the air. The direction of rifiling is ere

3. Striations

Striation are microscopic scretches ont eh surface inside the rifling impressions. No two firearms will produce exactly

* Rifling impression

Rifling impressions are impressions left on the surface of a bullet after it has been fired from a firearm with a rifled barrel.





DNA Analysis

15 03 2010

Q

A homicide has been committed. A middle-aged woman was chocked with a rope. The rope is the only evidence left at the crime scene. What would you do to solve this crime?

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A

In order to find out who the murderer is, you will carry out DNA ANALYSIS. There will be DNA sample left on the rope, which was touched by the murderer.

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DNA is the thing that makes you, you. Each person has a unique DNA with unique sequences. This helps C.S.I. figure out who is who by just analyzing evidences, such as blood, saliva, skin cells and figerprints, left at the crime scene.

Do you know the case of the thievery of Mona Lisa from the Louvre in 1911? If you do, do you know how the thief got caught? It was FINGERPRINT. The fingerprint left at the crime scene. It took a long time – two years – for the detectives to figure out who the thief was. It was a man names Vincenzo Peruggia, an employee at Louvre. He left some fingerprints on the protective glass that was shielding the Mona Lisa, and this led to his capture.

What would have happened if each person didn’t have a unique sequence of DNA? Do you now get why DNA is important?

All biological samples contain DNA, or deoxiribonucleic acid. It contains the genetic information that makes each individual unique. DNA differs between each individual; this is why blood, saliva, skin cells and fingerprints have DNA that can be analyzed in an investigation. DNA can be used as a link between a suspect and a crime. Only identical twins have identical DNAs. All cells in human body have DNA, but all DNA in one individual is same regardless of the part of the body we get the DNA from.

In the DNA lab, there are four steps taken to process DNA

  1. Extract
  2. Amplify
  3. Separate
  4. Analyze

1. Extract

The DNA analysts first get the DNA out of the cell to work with it. Bucal swabs are used most often to extract a person’s DNA, since it is painless and easy. Once they get the DNA, they take the DNA out of the cell. DNA is located inside the nuclear membrane. In order to get the DNA out, they lyse the cells and nuclei by dipping the swab into the lysis solution.

2. Amplify

Then, PCR, or polymerase chain reaction, is used to copy the DNA markers millions of times. DNA markers make up less than 0.01% of a person’s DNA, but using PCR makes them stand out despite the big proportion of the rest of the DNA. DNA sample is added to the replicating solution in order to amplify.

3. Separate

After amplification, DNAs have to be sorted by size. This allows us to determine different lengths of markers that are present. The sample from the PCR machine is moved to the Gentic Analyzer, which pushed the DNA through a very small tube filled with a gel-like substance. Small fragments move through faster than large fragments. This is like gel electrophoresis. A laser scans each group of DNA markers in the tube. Then, it records the time the markers exit and send the information to the computer.The computer shows the data from the Genetic Analyzer. A peak is formed each time a group of DNA fragments exit. The computer separates the DNA by size.

4. Analyze

Forensic DNA analysts use DNA profiles to compare DNA samples, because every person’s DNA contains a lot of information. A complete DNA profile will only match one person in one hundred quadrillion. The DNA profile gets processed through the CODIS database that finds the possible matches.