Forensics Questions

Re: the future of CSI

thegluups said:
In France, you are three different things a "CSI", who processes evidence (dusts prints , ....), a techinician who analyses everything, and an engineer, who supervises all that. They're all sworn officers ( in the sens that they get a flashy badge) but they can't wear guns ... or arrest suspects. So I guess that the only thing they really have in common with the TV CSIs is that they both get a shiny badge ...
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Ooops, forgot to define one of my terms in my last post here. In the US, a "sworn" officer is defined as an individual to takes an oath (hand raised, "I hereby swear ...) to uphold/enforce the laws of the land, and is thereby authorized --- by the law enforcement agency he/she works for --- to arrest suspects and carry a firearm. A sworn officer is issued a badge and credentials that say "police officer" or "deputy sheriff" or "special agent" ... and they must go through initial Academy training and then yearly/monthly updated training and "re-qualification" at the firing range to demonstrate their proficiency in the proper use of the firearms.

Many law enforcement agencies in the US also authorize civilians ("non-sworn" personnel) in their employ to carry firearms ... usually for their personal protection in the field. In this situation, the civilian typically goes through the same initial and year/monthly firearms training & qualification at the range as a sworn officer; but a "non-sworn" individual does not have the authority to enforce laws or arrest a suspect. The badge and credentials they're issued typically says "criminalist" or "forensic technician" or "forensic scientist."
 
Re: the future of CSI

this question is based on the csi game 3DOM anyway would you use luminol in real life on a shirt to bring up blood and is it also used a metal sink lol

thanks
 
Re: the future of CSI

major_csi_fan said:
this question is based on the csi game 3DOM anyway would you use luminol in real life on a shirt to bring up blood and is it also used a metal sink lol

thanks
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Not sure I fully understand the question. The Luminol procedure is typically used to visualize trace amounts of (often diluted) blood on an otherwise concealing backdrop so that the spatter pattern becomes visible to the naked eye. An example might be a suspected but invisible bloodstain or spatter pattern on a dark red or brown or navy blue shirt. In this test, the heme in the blood acts as a catalyst to accelerate the oxidation of the luminol reagent, thereby producing a bright bluish/greenish-white luminescence. But the test is only presumptive (many other catalysts can accelerate the oxidation of luminol), so a 'positive' luminol reaction doesn't prove the presence of blood. Not sure what all of this has to do with a metal sink.
 
Re: the future of CSI

However, the blood must be dry in order to react with the reagent used. Now, if the blood were freshly spilled, then luminol would not be the reagent in usage; LCV would.
 
Re: the future of CSI

VManso said:
However, the blood must be dry in order to react with the reagent used. Now, if the blood were freshly spilled, then luminol would not be the reagent in usage; LCV would.
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Essentially, the blood cells have to be lysed (broken) for the reagent to react with the trace amounts of iron in hemoglobin; and drying is a great way to lyse the cells.

As a side note: because luminol is such a non-specific indicator for blood, we would only use it as a last resort (for the spatter pattern info, or for an indication of where additional concentrations of blood might be found) when suspected blood stain was too diluted or decomposed to ID and categorize with the standard DNA and protein techniques. Defense attorneys have gotten pretty good at challenging the value of presumptive tests.
 
Re: the future of CSI

^^ Ken, does too much Luminol not affect blood pattern analysis.

I know, from experience, spraying a fluid onto a dried substance can cause it to streak more. If you were trying to work out what the blood had been wiped away with (hand/cloth/coat, etc) would the Luminol not alter the patterns left?
 
Re: the future of CSI

adorelo said:
^^ Ken, does too much Luminol not affect blood pattern analysis.

I know, from experience, spraying a fluid onto a dried substance can cause it to streak more. If you were trying to work out what the blood had been wiped away with (hand/cloth/coat, etc) would the Luminol not alter the patterns left?
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It definitely takes some skill to apply just enough Luminol to the substrate/surface so as not to cause the visualized patterns to streak. Unfortunately, I never seemed to acquire that skill because most of my visualized patterns did streak ... and I never really got that much useful information out of the visualized patterns, other than the indication that the suspect(s) had made an effort to clean up the scenes.

BTW, I'm guessing that (having confessed to reading my latest book In EXTREMIS, and being kind enough to say that he enjoyed it) VManso was probably chuckling to himself as he typed his e-message above. He's aware that I got a little carried away with my application of Luminol in that particular story. :)
 
Re: the future of CSI

^ That's great, thanks Ken. I'm writing something at the moment, and your information has been very usful. :) I like my science to be accurate.

So, if my suspect wiped away the blood left behind with a, oh, I don't know, a patterned glove, I'd be able to notice the patterns and match them a glove found, say, in the suspects home?

Oh, and something I wrote a while ago (but never posted) was entitled 'In Extremis' . :lol: Strange. I'd love to read yours, I must go and track your stuff down *makes mental note*.
 
Re: the future of CSI

Would fibers of such a glove (cloth or leather, not plastic) stick to the blood if it hasn't dried?
 
Re: the future of CSI

adorelo said:
So, if my suspect wiped away the blood left behind with a, oh, I don't know, a patterned glove, I'd be able to notice the patterns and match them a glove found, say, in the suspects home?

Oh, and something I wrote a while ago (but never posted) was entitled 'In Extremis' . :lol: Strange. I'd love to read yours, I must go and track your stuff down *makes mental note*.
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Well, if the glove was three-dimensionally irregular enought to leave a pattern in the blood smear, you would probably spot it with an indirect light source (angled flashlight). I really doubt that you'd see anything other than a vague outline of a glove using luminol reagents, but I never did master the trick of finely misting the luminol over the suspected blood stain.

IN EXTREMIS was suggested to me by my editor, and I thought it made a great title.
 
Re: the future of CSI

Dynamo1 said:
Would fibers of such a glove (cloth or leather, not plastic) stick to the blood if it hasn't dried?
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I think it would have to be a pretty fuzzy or ragged glove to leave fibers in the drying blood smear; but such fibers might be worth looking for, especially if you were hoping to find that glove (ideally still bearing the individualistic bloodstains!).
 
Re: the future of CSI

Know anything about guns, Ken?

Don't happen to know what the furtherst distance from the target GSR can be left on clothing is do you? Ruger Model 44 (44 Carbine)?

I should probably get off my butt and go to the range to figure this out, and I will one day, but I thought I'd try you first before I went out into the cold.

:D
 
Re: the future of CSI

adorelo said:
Know anything about guns, Ken?

Don't happen to know what the furtherst distance from the target GSR can be left on clothing is do you? Ruger Model 44 (44 Carbine)?

I should probably get off my butt and go to the range to figure this out, and I will one day, but I thought I'd try you first before I went out into the cold.

:D
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One of my 'generalist criminalist' jobs back in the late sixties and early seventies was firearms examiner. I don't recall the .44-Mag ranges for GSRs, but I'm guessing that you'd stop getting deposits around the four-foot distance from barrel to target, depending upon the wind and adherence characteristics of the target material. But if I were working this problem as a case, I wouldn't be able to trust 'average distance' data (too many variables, including the type of weapon, type and amount of gunpowder, etc), so I'd have to get off my butt and go out to the range also. :)
 
Re: the future of CSI

Thanks so much Ken. You're my little ray of sunshine on a dark day :D

I will go the the range at some point, and I'll let you know if the evidence I find co-oberates your info :) And if anyone else has any odd questions about guns, let me know and I'll figure those out too (if I can get my hands on the gun). :)

J
 
Re: the future of CSI

Other branches are Underwater Forensics, Forensic Medical Investigation Motor Vehicle Accidents,Environmental Forensics, Forensic Geology.
 
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