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forensics

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forensics

Post by joyce1938 on 19.04.15 14:07

Hello, I have never started a new subject before, forgive me if there is one already.  Last night late on tv was a programme that I felt I wanted to watch. It was called FBI and True Case. It happened to mention that lumenol used to find blood can destroy genetic materials after using it. Made me sit up and wonder about the samples that had been found, but I think not able to be identifiable?  Next I saw Forensic Detectives, this was saturday night late also. Using USA dogs to find bodies, each time it was positive, the dogs found what was expected.  Hope we might get more info from anyone that can come up with anything else on this subject.  joyce1938
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Re: forensics

Post by Richard IV on 19.04.15 14:27

@joyce1938 wrote:Hallo I hae never started a new subject before , forgive me if there is one already . Last night late on t v was aprogramn that I felt I wanted to watch. It was called FBI,and true case .I happened to mention that lumenol used to find blood , can destroy genetic materials  after using it . Made me sit up and wonder about the samples that had been found ,but I think not able to be identifiable ?   Next  I saw Forensic detectives ,this was saturday night late also . Using usa dogs to find bodies , each time it was positive ,the dogs found what was expected.  hope we might get more info from anyone that can come up with anything else on this subject .. joyce1938

That`s interesting - you`re right about the luminol - I didn`t know that.

"In recent years, blood visualization enhancing chemicals have regained popularity with crime scene investigators. The chemical of choice is usually luminol. Luminol is a chemical that when applied to bloodstains, even very dilute bloodstains, will cause the bloodstains to glow in the dark. Because it has several drawbacks as a presumptive test for blood, spraying luminol at a crime scene should be an investigator's last resort for detecting blood. The problems with luminol include:
[list="color: rgb(0, 0, 0); font-family: Verdana, Geneva, sans-serif; font-size: 13.3333330154419px; background-color: rgb(255, 255, 255);"]
[*]One of the empirical tests for determining if a stain is blood is its appearance. If it is a bloodstain, then it should look like blood. A bloodstain also has to be present in sufficient quantity to perform confirmatory testing and testing for genetic markers. This requires that the bloodstain is visible to the naked eye. The luminol reaction is at best a presumptive test for blood. If the stain is so dilute that it can only be visualized with luminol, then no further analysis can be performed to confirm the presence of blood.



[*]Luminol will give false reactions. Luminol will react with copper ions, copper compounds, iron compounds, and cobalt ions. It will also react with potassium permanganate (found in some dyes) and hydrated sodium hypochlorite (bleach).(6) Ferricyanide and plant peroxidases could also give false reactions.(7)



[*]Studies have shown that luminol will cause the loss of several genetic markers.(8,9)



[*]Because luminol is water based, it could cause, latent, possibly bloody impressions to smear. Luminol could also further dilute an already diluted stain. This may push the stain beyond the genetic marker analysis detection limits.

[/list]
Unfortunately, some crime scene investigators use luminol as their first choice for detecting blood. By using luminol in such a reckless manner, it is possible to lose valuable information from a bloodstain. When searching for blood at a crime scene, especially blood that may have been cleaned up, the investigator should first use a high intensity light to search for any traces of blood. Bloodstains are not easy to eradicate. Diluted blood will often leave a brownish stain where a person has tried to clean it. Blood also has a tendency to flow into floorboard cracks, into carpet padding, behind baseboards, etc. By conducting a thorough examination with a high intensity light source, the investigator can usually find these areas. These items can then be removed or collected and submitted to the crime lab for confirmatory testing.
Because luminol is so sensitive to dilute bloodstains, it is occasionally used to enhance bloody impressions (shoeprints, fingerprints, etc.). Luminol is not the best reagent for enhancing these impressions because of its water base. Better methods for enhancing bloody impressions use either rapidly evaporating organic solvents (such as merbromin and ortho-tolidine) or they use a water based chemical after treating the impression with a fixative (such as the amido black staining technique)."

http://www.crime-scene-investigator.net/blood.html

Was luminol used by the PJ forensics people? - I hope not.
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Re: forensics

Post by joyce1938 on 21.04.15 11:54

Richard IV, thanks a lot for your reply and other reading about it.  Has anyone else heard of these results before?  Didn't feel like anyone else was interested.  Maybe common knowledge to some.  joyce1938
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Re: forensics

Post by MRNOODLES on 21.04.15 13:43

Wiki

"if a crime scene is thoroughly cleaned with a bleach solution, residual cleaner will cause the entire crime scene to produce the typical blue glow",
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Re: forensics

Post by Nina on 21.04.15 15:15

@MRNOODLES wrote:Wiki

"if a crime scene is thoroughly cleaned with a bleach solution, residual cleaner will cause the entire crime scene to produce the typical blue glow",
The use of bleach for cleaning floors etc in Spain and Portugal is very common, or ammonia. So I am confident there will have been bleach used by the cleaner as a matter of course.

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Re: forensics

Post by onehand on 21.04.15 18:52

as far is told in the portuguese forensics, they made use of forensic lightning techniques and chemicals=reagentia to traces of blood and also semen, but i can only find they describe it used in the children s bedroom. The name of the product is not written down.
 
The problem was there was already done some basic forensic work by police officers, so there was a lot of white and red powder around in that bedroom.
 
Also there are more reagents for tracing small spots of bodily fluids or other relicts, they are not very popular , because all of them are able to react to enzymes or minerals in the specimen. Also they dilute biological samples often, but also could contain chemicals that destroy dna or at least alter it.
 
Luminol is a bit old fashioned as far as my experience go. The better approval today is use special forensic lights and dogs, this will leave everything in sutu and you still could save dna.
 
But there are a lot of very different household and cleaning  fluids on the market, that could contain indeed mineral components or even biological active enzymes that influence samples a lot. Sometimes even because it is in the layer direct under a spot of blood.
 
The portuguese report on their forensic activities is to be found at:
 
 http://www.mccannpjfiles.co.uk/PJ/5A_FORENSIC_4_5_7.htm
 
there is another problem that always will be playing a big role in serious crimes, you always have to choose what you do first, because looking for this, would or could influence the gathering of that. it is often a case of quick thinking was would deliver the most information in the shortest span of time. In portugal it could have been also a problem, because of distances and resources.
 
If you have to wait hours for the forensic people, you could lost several hard needed hours you could also have used for investigation. Only on tv you have the forensic people on direct stand by, that is not the reality in most true crime cases. 

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Re: forensics

Post by Joss on 21.04.15 18:57

A little bit of care has to be taken in certain settings, though, as other iron-based catalysts, such as potassium ferricyanide will also trigger the reaction. What’s more, Luminol will do its trick for some kinds of bleach, some copper compounds, fecal matter and even horseradish. The bleach is often the biggest problem at a crime scene as it may well have been used to clean away the bloodstain, resulting in an even, non-informative patch of glowing material.
An experienced investigator can tell the difference between blood and bleach because of different speeds of reaction, but it still makes it difficult to discover a bloodstain in some circumstances. And while spraying with luminol leaves the blood intact for further tests, it can remove other evidence, so its use is usually a lot more controlled than the free and easy spraying seen on TV forensic crime shows. Luminol, then, is not a universal solution for the detection of blood traces, but it is often effective. It’s not just a matter of detecting the presence of blood as, for instance, a hidden blood spatter pattern can provide valuable evidence about the direction of an attack or the weapon used.
The CSI team is not the only user of luminol – it has been employed in the laboratory for a range of tests for any combination of the components required in the reaction. So, for instance, the luminol glow can be used to determine hydrogen peroxide concentrations, or to detect the presence of other compounds that could react with the necessary catalyst and prevent it triggering the reaction. But there is no doubt that luminol and blood make for an excellent partnership.
http://www.rsc.org/chemistryworld/2014/04/luminol-csi-blood-forensic-podcast
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Re: forensics

Post by Hobs on 21.04.15 21:51

I remember  several years back in CSI  there was an episode where they were being filmed for some reality show and  one guy sprayed an item of clothing with luminol and showed up under  blacklight.

the camera man said it wasn't obvious and could the  technician spray it with more luminol to really amke the  pattern stand out.

The tech did so and the camera guy was happy>>
The tech's boss however wasn't as since he had used so much luminol, it had destroyed any DNA evidence.

The trick is to use the minimum to show if blood etc is visible rather than drown everything and damge or erase anything useful DNA wise

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Re: forensics

Post by joyce1938 on 23.08.15 12:19

Not certain if this right place to post this, but I decided to read the FSS Lowe reports from pj files.  I just don't know how to react to it.
It just seems obvious that so much of it just showed that it is not good enough to take into a court.  Not enough evidence that is positive, doesn't mean it could not be done by another place here someone would say.  Well, it's possible, mostly in this report, not enough DNA that was good enough to use and a lot of negative results as far as the person was concerned. Can someone talk us through it, maybe I have not done a good job of the readings.  joyce1938
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Forensics

Post by willowthewisp on 23.08.15 12:37

HIi Joyce,
Ask your self a question on the FSS DNA supposedly from Madeleine McCann,15 out of 19 markers with four markers (spoilt) result,88% match out of one hundred percent or one in a billion match to Madeleine?
The UK in a Court of Law relies on above Ten markers as evidence of DNA proof I believe, but the UK rules did not apply to this case as the Portugal PJ have overall charges to be brought against the parties associated to the case?
Ask a question of what happened to the residues of DNA that was left with the FSS after the tests, did the UK police destroy them or send them back to PJ in Portugal?
If they have been destroyed by the FSS,Why in an unsolved case of a disappearance did they do this, as if any evidence did turn up in this case they had something to match up to,or was this the reason to suppress findings?

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Re: forensics

Post by Get'emGonçalo on 23.08.15 12:54

@willowthewisp wrote:HIi Joyce,
Ask your self a question on the FSS DNA supposedly from Madeleine McCann,15 out of 19 markers with four markers (spoilt) result,88% match out of one hundred percent or one in a billion match to Madeleine?
The UK in a Court of Law relies on above Ten markers as evidence of DNA proof I believe, but the UK rules did not apply to this case as the Portugal PJ have overall charges to be brought against the parties associated to the case?
Ask a question of what happened to the residues of DNA that was left with the FSS after the tests, did the UK police destroy them or send them back to PJ in Portugal?
If they have been destroyed by the FSS,Why in an unsolved case of a disappearance did they do this, as if any evidence did turn up in this case they had something to match up to,or was this the reason to suppress findings?

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Re: forensics

Post by joyce1938 on 23.08.15 14:37

Hi there, well I think that if wanted some stuff returned, it had to be applied for?   Some was going to be destroyed after one month.  So the question, did anyone request having those back? I don't now now but if they had we would have heard I think.  I do understand what you mean, but the problem is would it stand up in court. I believe it was sent to another place to be tested too, wasn't it, where was the other place?  It seems like a good job was made of all the not enough to test sort of stuff.  joyce1938
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Professors declare breakthrough in DNA analysis

Post by willowthewisp on 03.12.15 13:42

Professors have stated that they can now determine from DNA of the genetic code to prevent illness that may be genetically inherited through your parents, that this could prevent certain inherited codes of the DNA that could be likely to become a disease within the body.
It's a pity that the FSS and John Lowe may have legally allowed the "Home Office"to use directives, to Destroy samples of DNA from a still missing person, Madeleine McCann in 2007?
How many times have the UK Police Force allowed for the destruction of DNA samples in unproven cases of that person's whereabouts to be undertaken?
We certainly now know of at least one case in the UK, from correspondence from FSS and Home Office directives of what they proposed to do with the DNA collated from the Renault Scenic?

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