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.





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.





Forensic Photographer

16 03 2010

When you see crime scenes on TV, you can see people taking pictures here and there.

Photography is simply an art of taking and processing photographs. However, FORENSIC photography is a little bit different. Forensic Photography is an art of reproducing an accurate image of the crime scene for the laboratory and the court.

Forensic Photographers take pictures of…

  • Crime scenes
  • Gunshot wounds
  • Bitemarks
  • Weapons
  • Trace evidence
  • Autopsy procedures

(From www.all-about-forensic-science.com)

Forensic Photographers help out the process of investigation by supporting the laboratory by documenting and enhancing the evidence. You should not think that it is an easy job of just taking random pictures of the crime scene. Documentation of evidence is extremely important in the whole process of investigation. If the photographer misses an evidence, that changes the fate of the victim. You need a high level of responsibility to do this work. The most important things that the photographer should take pictures of are bloodstains and cuts. The overall picture of all evidence collected together are taken, and important evidences are taken as closeups. The important evidence is, as I said, the bloodstains and cuts.

Also, the forensic photographers require special techniques. Sometimes, the evidence is too small that photomacrography, a technique using bellows to increase magnification, has to come into place. There are lots of other techniques, including alternate spectrums, which is a technique used to see evidences in different lights in order to see them in a most clear state, and using infrared film for gun shot residue on clothing.

Like all most of other forensic jobs, you need a strong stomach. Sometimes, you will have to take pictures of victims that are very inhumanely distorted due to an attack. Also, you need to know the court procedure, for you are the one who will be presenting the evidence to the jury.

In order to perform all the special tricks, it is best if you major in photography. You will get to encounter advanced technology as you take pictures at crime scenes, since you will always have the best equipment. And yes, the equipment costs a lot. However, since it is an important job that requires a good quality, you need to be ready to invest that money.

This is a video that helps us understand what the career in forensic photography really is.





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.





What happens AFTER the investigation?

7 03 2010

After all the investigation is done at the crime scene, what happens?

All evidences collected and the corpse are sent to the laboratory for in-depth examination.

The scientists who work in the forensics field come together and work to solve the hidden mystery of the crime by scientifically analyzing the case. The scientists referred here are specialists in many different fields. Only a few really majored in forensic science. Others majored in Criminology, Genetic Biology, Molecular Biology, Toxicology, Pathology, Serology, Computer, Accounting, Anthropology, Odontology, Ligustics, Enthomology, Engineering, Environmental Science, Art, Photography, and many other subjects. One is required to take a Ph D programme to work at a good agent, and to become a forensic pathologiest, who examines the dead human bodies to figure out the cause of death, he/she needs to has MBBS degree, followed by MD in forensic medicine.

This is a list of things that forensic scientists usually specialize at

1.) Forensic Chemical Science

  • Chemistry
  • Narcotics
  • Explosives
  • Toxicology
  • Pharmacology

2.) Forensic Physical Science

  • Physics
  • Ballistics
  • Image processing
  • Speaker recognition
  • Lie detection
  • Instrumentation

3. Forensic Biological Science

  • Biology
  • Serology
  • DNA finger printing
  • Osteology
  • Odontology
  • Anthropology

4.) Forensic Documentation Science

  • Ink analysis
  • Paper and fiber analysis
  • Cyber Forensics
  • Handwriting analysis
  • Credit card frauds

With specializations in these things, forensic scientist gather the puzzle pieces together to determine how the victim got killed.

To see what they really do, click on “Forensic Science” tab on the right.