CSI:Chromatography

CSI use chromatography to find out what type of pen a letter or note as written with. For example if you were given a letter with three possible pens it could of been written with nowadays it would just be tested in a machine. But before machines they had to do it the long way.

What you would do is take ink from the letter and put it on a strip of paper. Then put a tiny bit of water in a beaker and wait to see what pattern it left. After this you would draw a line 2 cm from the bottom of a strip of paper. Put three equally spaced crosses on the line then put a small dot from each pen on the crosses. You would get another beaker and fill it bellow the ink line with water and then wait to the pattern the each pen left. You would then match the ink from the letter and the ink from the pen up to find which pen it was wrote with.

CSI:DNA Fingerprinting

The letters DNA stand for Deoxyribonucleic acid. DNA Fingerprinting was discovered by Proffesor Sir I Geoffries. If you have a cell inside that cell is a neacleus and inside the neacleus is the genetic material. This is an enourmous long ,thin shape and that varies a little between each person.



It is a like a book written with four different letters of the alphabet and each human body is made up of six thousand million of them. If we were reading through this book and we could translate it. For example if it said Mary had a little lamb and one of these regions says Mary had a lllllllittle lamb there is a different pattern. These stutters vary in person to person and this is accidentally how he found out about DNA fingerprinting.

CSI:Blood Types

Blood is made of a liquid (plasma) this makes up 55% of blood in your body.

Today blood types do not help forensic scientists. It used to but when DNA anaylas came along in the 1980's it wasn't needed. Karl Landsteiner won the nobel prize for his discovery of blood type in 1901.

These are the different blood types.

Blood stains are needed in CSI to get the DNA composition of the blood. Another reason is blood stains leave a pattern and this can be very important in a crime scene as to what happened. For example how many blows someone had and in what direction. What movement the victim had during the crime.

CSI:How they do fingerprints

Our fingers have friction ridges these are what help us grab hold of objects without them slipping away. They also have another purpose, for CSI, that is to get fingerprints(Info :no two fingerprints are the same). If we touched some ink and then put our finger on a peice of paper we would see theses friction Ridges.

There are alot of fingerprint patterns these are some of them:

The Arch ,The Loop ,The Whrorl

The history of fingerprinting started in 1880 by an english man named Henry Fauld. His system replaced body-measurement system called anthropometry. A couple of years years later another englishman named Francis published a very well known text book called 'fingerprints' were he talked about the different fingerprint patterns and hoe they were used to trace peoples identity.

The use of fingerprinting has helped CSI to catch crimals for example a young boy had left his fibgerprint on a gun that was fired from the top of a school building thre is also James Earl Ray who left his finderprint on the weopan that he used to kill Martin Luther King.

Fingerprinting is the most important tool in CSI.

CSI:Crime Scene Investigation

This is my blog about the Forensic Science Service.
These are people who help the police to capture criminals.