forensics

Tuesday, September 1, 2009

Fingerprinting as forensics

Have you ever wanted to be like Inspector Clueso or like a CSI person or wondered how the things they did worked? One of the most important "clues" in forensics is fingerprinting. There are many different ways to develop fingerprints, some may seem obvious or others may be impressive or mysterious looking. For example, have you ever been watching CSI or NCIS and they produce a gaseous fume and some how it makes the fingerprints vi sable? This may seem like magic or you may say "that's just a TV thing." Well I have news for you...its not! Have you ever heard of something called cyanoacrylate? no? How about superglue? Superglue's particles , when heated, tend to stick on the oils leftover from the ridges on your fingerprint. And when it dries, it stays. We also have access to chemicals like Vacuum Metal Deposition or VMD. This is usually used on items like a plastic bag but can be used on objects that have been submerged in water! You would that water would wash away the print but when the VMD dissolves a layer of gold followed by Zinc the print becomes visable. Although today recycled bags are more common, so for those they made a VMD that dissolves the silver once again leaving the print.

People wonder: How did we discover this stuff? Well it all started in 1823 with a man named Purkinje who classified fingerprints as 9 types.

Then 20 years later in 1870 Dr. Henry Faulds realized the importance of fingerprints as a means of identification and devised a means of lifting them via ink. Then in 1892 a policeman named Juan Vucetich booked Francis Rojas, a woman who murdered her 2 sons, and her file included Rojas' fingerprints. Then everything shot up exponentially and today in 2009, America holds about 100,000,000 fingerprints of criminals in the largest AFIS building in the US.

Today there are many ways of developing and collecting fingerprints. Another modern technique for developing fingerprints is using a chemical called Silver Nitrate. This can be found in black and white photographic film. When the chlorine in the oils of your hand mix with the silver nitrate and it creates silver chloride. This makes it visible in a UV light and makes a reddish brown color. This can be followed by collecting the fingerprint by taking a picture of it. Another rather "old fashioned" method is to use ninhydrin. This surprisingly takes a very long time to react with the oils in your hand and can take hours. If you heat it, it wont take as long and the print only lasts a few minutes. So if you spray on a mixture of water and starch it will stay for weeks maybe months. You can collect the fingerprint if the object is small enough to take back to the lab. There is also the classic powder and brush to develop it and then lift the fingerprint with tape. The last method of collecting a fingerprint is using Iodine. When it is heated it releases fumes that react with the oils left over from the fingerprint and makes it visible with a brownish color. You can also lift fingerprints by pressing it into a soap, wax or putty.

There are 3 different types of fingerprints: Latent, plastic, and direct. Latent fingerprints are left from the oils on the ridges of your finger. It is invisible to the naked eye, therefore it has to be developed. The second is plastic like if you touch something plastic it will leave a negative impression of your fingerprint. This happens in things like a bar of chocolate, candles, newly painted objects, fresh cement or in the sticky stuff on envelops or stamps. Direct is a visible fingerprint that is made visible by things like flour, soot, dust ink ect.

Monday, August 31, 2009

Handwriting Analysis in Forensic Science

This is known as the Lindbergh kidnapping of 1932. Where someone wrote 14 ransom notes to a family. When the police got a hold on these letters they had no trouble identifying them as all the same person, but had a great deal of trouble identifying the culprit: Richard Bruno Hauptmann. They figured out the kidnapper's identity by using techniques that Albert Osborn discovered in 1910. Osborn recognized the significance of handwriting analysis, and he devised a means and techniques for matching them. Many of the techniques still used today. The technique used to determine the culprit in this case was to look for the differences. Anyone can look at the similarities with a fair amount of accuracy but to look at the differences, especially the ones that matter, is not hard and often requires years of training and practice. Handwriting changes over they years. Also, each time you write a word, it will look different (at least some parts will). The letter's will change depending on where they are placed in the word/sentence. The trick is, the one that Osborn discovered, is what letters don't change; better yet, what parts of the word/letter don't change.

Another important thing to remember is that you have to distinguish between style characteristics and individual characteristics. Forensic Scientists want to examine the individual characteristics. Things like the sizes of the letters: width, height; the curves of the letters, the slants. Also if the letters are "slurred" together or connect. How close the words are together, or how close the letters are to other letters, the pressure put on the pencil on down strokes, upward strokes. Also the placement on the line is important. Example: if the letters on one line are so tall that they intersect with letters on the line above it. The margin left over is important as well.

These are just a few techniques that are used in identifying the author of an unknown document. To develop the skills required to work in this field would take dedication, and years of training. Even with years of practice, the validity of handwriting analysis may be iffy in court. Handwritten documents would go into the questioned documents folder. From there analysts will analyze it and come to a conclusion.

These are pictures that of a forging assignment that we did in class where the top is the original, the middle is a free hand forge and the last is a trace forgery.

This is the origional:

This is the freehand forge:

This is an example of a traced forge:

The above is a check which Andy correctly identifyed as me. I wrote it. then tore it up. He then put it back together and taped it and then correctly identifyed it as me.

***The latter of the pictures was taken courtesy of A. Platt. Thank you.

Sunday, August 30, 2009

Hair Analysis used in Forensic Science

During a crime, at least two people interact. When they interact, both of them take something away and leave something behind. In some movies you may see specialists analyzing hair and fibers through a microscope. Well since humans lose about 100 hairs a day, hairs are a perfect thing to find and use at a crime scene. It is very common for hair from the owners pet tok transfer to the criminal and then to be left at the crime scene. There are also several different types of hairs that differencate between cat hairs, dog hairs, human hairs, ect. Some of these disctions may be what the outside looks like. Which can be classified into three groups:

Coronal:

or a Spinous:

And Imbricate:

The importance of hair in forensic science was first reconized in The Principles and Practice of Medical Jurisprudence by Alfred Swaine Taylor and Thomas Stevenson. This has a chapter on the importance of hair in a crime scene/forensic science. This chapter has refrences of cases that hair was used in the solving of the crime, drawing of the hairs under magnafication, and parts of human hair which include: the cuticle, medulla and cortex. The Cuticle is the outside of the hair and is like a protection. The Medulla is the innermost part of the hair. The Cortex are the cells between the Cuticle and the Medulla.

Here are some picture of some hair analysis that we did in class and lab:

Saturday, August 29, 2009

The Use of Blood in Forensic Science

There are 4 different types of Blood: A, B, AB, and O. This is based on the presence or absence of antigens on the surface of the red blood cell.There are technically 2 different types: A and B. AB is when you have both types and O is when you have none. When you give blood to another person, if they have a different blood type than of which you give them, then the results can be fatal because the antibodies in one blood begin to attack the other. So if you are O then you are the universal donor because you have neither. Where as AB is the universal recipient because it can accept blood from A, because it has A in it, and B for the same reason, AB because it has both A and B in it and O because it has neither. This all started in 1901 when an Austrian named Karl Landsteiner discovered the human blood groups. He made it possible to determine blood types and therefore made transfusions possible. Transfusions are intended to save a lives. A transfusion is taking blood from one blood type and giving it to someone with the same blood type to help them with things like massive blood loss due to trauma. Although various diseases can be passed from one to another through transfusions like HIV, Hepatitis B and C, Malaria etc. The RhD is also a very important factor. If the RhD is not the same then the consequences would be the same as mixing two different types of blood. RhD refers to the absence (-) and the presence (+) of the Rhesus, a type of antibody. This was discovered in an experiment in 1937 where Karal Landstiner and Alexander S. Wiener discovered that rabbits, when immunized with rhesus monkey cells, created agglutinates, an antibody. Which is the red blood cells of many humans.

The picture below better explains blood types, the antibodies in them and the antigens in them:

The above picture is of a blood typing kit we did in class

Friday, August 28, 2009

Final Test: putting it all together and solving the ultimate crime

Our ultimate test was one big crime scene investigation. When we first walked in we saw a bag of crack (not real of course), a shoe, a hairband, an earring, an ripped up note, a glass with fingerprints on it, and some blood. There were many different suspects. It was our job to figure out what took place and who did what. We all of a suddenly assumed it was a drug deal. Our team first examined the drugs. This means that it probably involved Sam Tilson, Kooladria Jones, and/or Mr. Popadines. But especially Kooladria because she was a woman and there was obviously a woman involved. We used common sense and came to the conclusion that a drug deal involves 2 people or more. We found the blood type to be AB. This further pointed out Kooladria. The writing looked a bit like Kooladria's and Mr. Kelly's handwriting. But with further examination we figured it was Mr. Kelly's handwriting. There were two samples of hair: some synthetic hair and a white males hair. Kooladria was a hair designer and had bullet proof hair. And the white male further pointed out Mr. Kelly. The fingerprint left at the scene was an ulnar loop which matched Mr. Kelly's handwriting.

My scenario: Mr. Kelly went to Kooladria, a well known hooker, and figured she was probably into drugs. And because of kooladria's background of taking drugs she accepted. Mr. Kelly was very good at staying in the dark because he had no record. Kooladria accepted and began to bargain with Mr. Kelly. Mr. Kelly, upset from losing his tennis match, was not willing to be ripped of and said "NO! EITHER YOU HAVE THE MONEY OR YOU DON'T!" She said she didn't have the money but took the drugs anyway. When she did this Mr. Kelly viciously attacked Kooladria (he was also probably on drugs) and preceded to beat her and she got one good slap across his face with her nails. That was her chance and she took it: she ran. But leaving some of her belongings behind.

Things at the Crime Scene: