Why is it technically impossible to get away with a crime thanks to forensic evidence?
Over the past nine weeks I have done extensive research on the topic of forensic investigation. I have studied DNA, fingerprinting, and trace evidence techniques and studies. The best response I can come up with is the follow:
CSO's (Crime Scene Officers) have a bulletproof plan of attack on crime scenes. They isolate and quarantine the area. Sweep every inch for footprints, blood, hair follicles, anything which can create a lead. They then spend hours analyzing evidence and data until they come up with solid evidence which points them to a suspect.
Though Some criminals have gotten away in the past, in todays society, that percentage is decreasing rapidly. New tools, and investigative teachings are making it harder and harder to get away. In the end though science will prevail, they will get caught, and they will go to prison. Case closed.
Sunday, May 29, 2011
Overview of Wiki
WIKI PAGE:
http://tocatchacriminal.wikispaces.com/
This wiki page will cover the following information that I have learned over the past 9 weeks of research. It will organize my studies into 3 major sub-headings, DNA, fingerprints, and tools. This Wiki will cover all the specifics of forensic investigation and analysis. I hope you enjoy it.
http://tocatchacriminal.wikispaces.com/
This wiki page will cover the following information that I have learned over the past 9 weeks of research. It will organize my studies into 3 major sub-headings, DNA, fingerprints, and tools. This Wiki will cover all the specifics of forensic investigation and analysis. I hope you enjoy it.
Friday, May 20, 2011
DNA Forensics
DNA forensics has and can be used for identification purposes. There is one distinctive issue, in DNA trace and matching only 1/10 of a percent of DNA differs from person to person, about 3 million bases. This means that only a very small part of human DNA is different from person to person. There is a chance though that two people have identical probes in different parts of there DNA. This is very slight and unlikely.
At a crime scene DNA collection can come from a variety of sources including blood, hair, skin tissue and bone. These specimens are then collected and there DNA sequence is observed. CSO's split the DNA and see which base pair in which order connect to the sequence. The order in which these pairs are arranged is different for every person. The DNA from the suspect is then collected and compared with the sample sequence. Usually one single match of a few base pairs isn't enough for prosecution, but four over five matches in different areas of the sequence may be enough.
There is a chance that another person may have contributed but the chances are very unlikely. DNA forensics has all to do with odds. When convicting an individual the odds of an eye-witnes testimony are 50:50. DNA provides better odds when prosecuting. The more probes that match, the higher the odds. In the end it all comes down to what the judge and jury accept as sufficient evidence.
Website:
, . "DNA Forensics." Human Genome Project Information. 2009. U.S. Department of Energy. 20 May, 2011. <http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml>
At a crime scene DNA collection can come from a variety of sources including blood, hair, skin tissue and bone. These specimens are then collected and there DNA sequence is observed. CSO's split the DNA and see which base pair in which order connect to the sequence. The order in which these pairs are arranged is different for every person. The DNA from the suspect is then collected and compared with the sample sequence. Usually one single match of a few base pairs isn't enough for prosecution, but four over five matches in different areas of the sequence may be enough.
There is a chance that another person may have contributed but the chances are very unlikely. DNA forensics has all to do with odds. When convicting an individual the odds of an eye-witnes testimony are 50:50. DNA provides better odds when prosecuting. The more probes that match, the higher the odds. In the end it all comes down to what the judge and jury accept as sufficient evidence.
Website:
, . "DNA Forensics." Human Genome Project Information. 2009. U.S. Department of Energy. 20 May, 2011. <http://www.ornl.gov/sci/techresources/Human_Genome/elsi/forensics.shtml>
Friday, May 13, 2011
This video shows the basics of computer forensics, and information technology. They talk about how an independent company is hired to investigate and find the truth, "hidden in the computer." Even when you delete your browser history, or clear your cache, your computer always leaves a permanent mark of whatever you do. Sort of like a digital fingerprint. I hope you enjoy.
Film and Video:
, . "STEM Careers for Students: Volume 02". Computer Forensics Specialist . 2010. <Discovery Education: http://player.discoveryeducation.com/index.cfm?guidAssetId=E039D2D7-B001-4190-98EC-364A5E63FFE0&blnFromSearch=1&productcode=US>. 13 May, 2011.
Investigating a Crime Scene
In this video you will see how CSO's (Crime Scene Officers) investigate and collect data from a crime scene. They go over the techniques and put them in a real life situation. They show you how a crime that happened in the past would have been investigated if modern forensics techniques were used. At the end there is a question. If you choose you can answer it in the comment section.
Film and Video:
, . "Discovery Education". Scientific Investigation: Modern Forensics. 2004. <website: http://player.discoveryeducation.com/index.cfm?guidAssetId=890CCA23-7567-40E7-9766-49179E21E14B&blnFromSearch=1&productcode=US#>. 13 May, 2011.
Friday, May 6, 2011
Forensics Science Lab Setup
Each major city has a Crime lab which is dedicated to the types of problems and crimes associated with the area. For example, in a city with drug trafficking along state or international borders there is usually a Federal forensics lab which can deal with drug investigation. A typical forensics lab breaks into the following subsections, hair and fiber/trace analysis, drugs and technology, forensics photography, ballistics and firearms analysis, dental/odontology, anthropology, fingerprinting, medical examiner/coroner, questioned documents, serology/forensic biology (DNA), evidence collection teams (CSI), evidence intake and security, records and archive section, support staff.
Most labs are organized so that each section is separated from the others based on what equipment is used in what department. One of the most important things in a crime lab is the handling and passing down of evidence. From the time it comes off the crime scene, evidence must be catalogued and signed for every person that touches it. Whom ever comes into contact with evidence folders or bags has a certain responsibility to maintain the security of the evidence. Evidence tampering is a crime punishable by law, this is why evidence handling is a difficult area.
Book:
Fisher, Barry and David Fisher, Jason Kolowski. Forensics Demystified. : McGraw-Hill, 2007.
Most labs are organized so that each section is separated from the others based on what equipment is used in what department. One of the most important things in a crime lab is the handling and passing down of evidence. From the time it comes off the crime scene, evidence must be catalogued and signed for every person that touches it. Whom ever comes into contact with evidence folders or bags has a certain responsibility to maintain the security of the evidence. Evidence tampering is a crime punishable by law, this is why evidence handling is a difficult area.
Book:
Fisher, Barry and David Fisher, Jason Kolowski. Forensics Demystified. : McGraw-Hill, 2007.
Friday, April 29, 2011
Calculating Rarity of Fingerprint
Finger prints have been used for identification ever since the 1800's. The process was lengthy and required the entire print. The reality of it is that at a crime scene, a CSO (Crime Scene Officer) may find over one hundred prints and most of them are partials. Recently, forensic scientists have come up with a way to mathematically calculate the rarity of a print.
Knowing how rare a fingerprint is can help CSO's determine which prints are helpful to the case. The software that calculates this gives a print a series of points and compares it with others. This computer then compiles the evidence and calculates rarity of the print. To date most CSO's do this calculation by hand
“They might find hundreds of prints at a crime scene, and right now the analysis is done intuitively by human examiners,” Dr. Srihari said. “But we can calculate that.”(Dr. Srihari 2010)
Newspaper or Magazine Article:
Bhanoo, Sindya. "Calculating the Rarity of a Fingerprint." The New York Times December 10, 2010: Science, online.
Knowing how rare a fingerprint is can help CSO's determine which prints are helpful to the case. The software that calculates this gives a print a series of points and compares it with others. This computer then compiles the evidence and calculates rarity of the print. To date most CSO's do this calculation by hand
“They might find hundreds of prints at a crime scene, and right now the analysis is done intuitively by human examiners,” Dr. Srihari said. “But we can calculate that.”(Dr. Srihari 2010)
Newspaper or Magazine Article:
Bhanoo, Sindya. "Calculating the Rarity of a Fingerprint." The New York Times December 10, 2010: Science, online.
Thursday, April 21, 2011
CSI Improvised Tools of the Trade
Though all CSI's go through difficult and extensive training, sometimes what's learned in the classroom doesn't help in the field. When they encounter obstacles that can not be overcome using there nifty kits, CSI's are required to think "out of the box". Many times a CSI has faced a situation in which they must improvise and find a solution to there problem with the tools given to them. Many "tools of the trade" started as improvisational gadgets thought of by CSI's in the field.
For example, one tool being the Blue Light Special, was created in 1994. This tool was a hand held blue light which allowed Investigators to find urine, semen, and saliva samples at the scene of the crime. Pre-Blue Light Special, the only lights for finding these specimens where huge crime-lab lights which costed upwards of thousands of dollars. So, CSI's had to collect everything they believed contained evidence then bring it back to the lab to examine it. Now with The Blue Light Special the crime scene would no longer have to be completely disturbed.
Another device which started as an improvised gadget is the Eagle-Eye Pole. The Eagle-Eye Pole is a pole that you strap a camera to the end of to be able to take birds-eye view photos. Prior to the Eagle-Eye CSI's would have to call in tree trimers or use latters to raise themselve from the scene to be able to take a photo.
Newspaper or Magazine Article:
Warrington, Dick. "On the Scene: Improvised Tools of the Trade."Forensics Magazine : .
For example, one tool being the Blue Light Special, was created in 1994. This tool was a hand held blue light which allowed Investigators to find urine, semen, and saliva samples at the scene of the crime. Pre-Blue Light Special, the only lights for finding these specimens where huge crime-lab lights which costed upwards of thousands of dollars. So, CSI's had to collect everything they believed contained evidence then bring it back to the lab to examine it. Now with The Blue Light Special the crime scene would no longer have to be completely disturbed.
Another device which started as an improvised gadget is the Eagle-Eye Pole. The Eagle-Eye Pole is a pole that you strap a camera to the end of to be able to take birds-eye view photos. Prior to the Eagle-Eye CSI's would have to call in tree trimers or use latters to raise themselve from the scene to be able to take a photo.
Newspaper or Magazine Article:
Warrington, Dick. "On the Scene: Improvised Tools of the Trade."Forensics Magazine : .
Friday, April 15, 2011
Fingerprints in Forensics.
In the begging fingerprints were first thought of as a form of identification by Sir Henry Edward in 1896. He classified finger prints into the major categories of whorls, loops, and arches. Finger prints where given a set of numbers which were used as a fraction to identify the 10 different fingers in a coded sequence. A fingerprint was given a number code depending on the type of pattern and the finger the print came off of. This system of classification consisted of over 1024 codes which helped catch criminals who had many different identities, aliases.
Criminals who where already convicted before were fingerprinted and inputed into the system. Their prints were matched and compared with other prints found at different scenes. The system did have however have its flaws due to the fact that all 10 fingers needed to be collected. Later on with the invention of computer systems, finger prints became easier to collect and compare. The ability to match prints progressed faster and faster over the years.
To compare prints investigators looked at the ridges and where they start, end, and split. With computers this process became easier where a certain system could automatically record the ridges, whorls, arches or loops. These where then compared to the prints collected and listed in order of most comparable.
Website:
, . "Fingerprinting ." ORACLE ThinkQuest. . . 15 April, 2011. <http://library.thinkquest.org/04oct/00206/text_nts_fingerprinting.htm>.
Criminals who where already convicted before were fingerprinted and inputed into the system. Their prints were matched and compared with other prints found at different scenes. The system did have however have its flaws due to the fact that all 10 fingers needed to be collected. Later on with the invention of computer systems, finger prints became easier to collect and compare. The ability to match prints progressed faster and faster over the years.
To compare prints investigators looked at the ridges and where they start, end, and split. With computers this process became easier where a certain system could automatically record the ridges, whorls, arches or loops. These where then compared to the prints collected and listed in order of most comparable.
Website:
, . "Fingerprinting ." ORACLE ThinkQuest. . . 15 April, 2011. <http://library.thinkquest.org/04oct/00206/text_nts_fingerprinting.htm>.
How does forensic evidence help track and catch criminals?
Where ever you go, what ever you do, you always disturb your environment. Whenever you walk into a room you either leave something or take something with you on the microscopic level. There are hundreds of microscopic pieces of evidence that can link you to specific place at a specific time. Naming a few being DNA trace, fingerprints, hair, sweat, saliva, skin even the brand and chemical make up of the cologne you were can link you to a crime scene. Hours of chemical analysis of a crime scene can bring up hundreds of pieces of evidence that can narrow down suspects. Though the process may not be as fast as you see on CSI: Miami, the idea of it is dead on. Throughout the next 18 weeks of research I hope to better understand how is it that getting away with a crime is technically impossible, thanks to forensic evidence.
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