Posts Tagged ‘Forensic Nursing DNA Test’

Different Sources of DNA

October 12, 2007

There are many different sources of DNA an investigator may collect DNA from. Saliva is the last of the body secretions that DNA can be extracted from, as well as tears, sweat, urine, fecal matter, and vomit. Saliva is not usually collected directly. The investigator will collect things that have been in the suspect’s mouth, such as chewing gum, straws, cigarette butt, lipstick, eating utensils, stamps, and envelops. Hair is one of the most common items used to get DNA. The investigator needs the root to analyze. If there is a rape case, they will need to get a pubic hair if possible. If human remains are found without flesh, the bone marrow is the best choice to take a sample from. If the body still has tissue, then the liver or spleen are the best choices. Teeth are also very good to use, as the teeth are the most resilient part of the body.


Is DNA effective in identifying persons?

April 19, 2007

DNA identification can be quite effective if used correctly. Portions of the DNA sequence that vary the most among humans must be used. Also, portions must be large enough to overcome the fact that human mating is not absolutely random. Consider the scenario of a regular crime scene investigation, for example: Assume that type O blood is found at the crime scene. Type O occurs in about 40-45% of Americans. If investigators type only for ABO, then finding that the accurate “suspect” in a crime is type O really doesn’t reveal very much. If, in addition to being type O, the suspect is a blonde, and blonde hair is found at the crime scene, then you now have two bits of evidence to suggest who really did it. However, there are a lot of Type O blondes out there along with brunettes.

If you find that the crime scene has footprints from a pair of Nike Air Jordans (with a distinctive tread design) or another distinct type of shoe and the suspect, in addition to being type O and blonde or brunette, he is also wearing Air Jordans or another specific shoes with the same tread design, then you are much closer to linking the suspect with the crime scene, assuming it is a male. In this way, by accumulating bits of linking evidence in a chain, where each bit by itself isn’t very strong but the set of all of them together is very strong, you can argue that your suspect really is the right person, as long as you have all the important evidence. With DNA, the same kind of thinking is used. You can look for matches (based on sequence or on numbers of small repeating units of DNA sequence) at a number of different locations on the person’s genome; one or two, maybe three aren’t enough to be confident that the suspect is the right one, but four or five can be used and are used and a match at all five is rare enough that you, a prosecutor or a jury can be very confident, that the right person is accused an acquitted.


Innocent Prisoners

March 19, 2007

I have been doing some research on people that are wrongfully imprisoned. I find this a very interesting topic, as I am sure there were hundreds or maybe even thousands of inmates that were on death row and died before the courts allowed DNA to be presented after a person was convicted. There are an estimated 15-20% of the U.S. inmates that are innocent of the crimes they were convicted of. There have been several cases where the inmate was released from prison after the courts allowed the DNA to be entered after the person was convicted, and was certainly found to be innocent. I just can’t imagine being in prison, possibly serving a life sentence, or even on death row knowing that I was totally innocent. I cannot find a date that the first inmate was released from prison after being found innocent though. I believe that with the DNA database in place now that a lot more cases will be dismissed or they will find the right person responsible for the crime.


%d bloggers like this: