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Ninhydrin Prints Developing?

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Big Wullie
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Re: Ninhydrin Prints Developing?

Post by Big Wullie » Sun Apr 29, 2012 5:30 am


Yes I am looking at a case from years ago: ... 00&bih=805

It is alleged there was a bloody fingerprint on a wall which was then sprayed with the above substances.

My question really now would have to be this:

If there was a bloody fingerprint it would have been visible therefore there would have been no need to spray any substances would there ?

It just so happens Peter Swann has been involved too at one stage confirming it was blood despite every other expert now saying there was no way of telling.

Graham F
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Re: Ninhydrin Prints Developing?

Post by Graham F » Sun Apr 29, 2012 8:27 pm

Could not get the link to work, so I have no background on the case you are referring to.
If there was a bloody fingerprint it would have been visible therefore there would have been no need to spray any substances would there ?
Not necessarily so. The blood like substance may have been too indistinct to determine if the latent print had sufficient quantity/quality of minutia for comparison and/or identification. One way to improve/enhance the print after initial photography would be to use say, Ninhydrin. This is also known to enhance latents that may be contaminated with blood, not just unseen amino acid latents on porous surfaces. I always use the term blood like (or similar). I never state that the print is in blood, as this has not been determined at that time.

Iodine develops sebaceous deposits, whereas, Ninhydrin reacts with the amino acids in a print. Iodine will fade very quickly, but with heavy contamination a reduced quality latent may still be present weeks later, but this is not the norm. Ninhydrin can fade quickly, but can also stay visible for years. The volume of amino acid in the print will be a great factor in this. Accelerating the treatment process and how the exhibit was stored post processing will also have some bearing on the latent staying visible.

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Re: Ninhydrin Prints Developing?

Post by Neville » Sun Apr 29, 2012 10:17 pm

Sorry Amy
the subject has been totally hijacked.

Hi Wullie
Graham is correct, actually getting a good quality print in blood is quite rare as it requires just the right amount of blood with just the right amount of pressure and the timing has to be right otherwise the blood gets too thick, so the use of an enhancer is normal. I personally prefer ninhydrin as it is easier to work with, easier than amido black anyway.

My opinion is that anything SWANN says needs to be taken with a pinch of salt (preferably over the left shoulder) I base this opinion on his past comments about New Zealand experts. In particular his comments re Mr SWA...... It appears SWANN has a phobia about tall people, he finds them threatening! As I am about the same height as Mr Swa..... he therefore must be threatened by me. Oh well.

We in NZ are not allowed to make a comment like, it was blood, that is for the ESR staff to determine, we also are required to say blood like substance.

Many years ago I was guilt of stating "it was in blood" in court then having to back peddle very fast, so SWANN may well have said it in the past but may not now.

Regards Neville

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Big Wullie
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Re: Ninhydrin Prints Developing?

Post by Big Wullie » Mon Apr 30, 2012 2:44 pm

Neville, Graham

Many thanks for your replies.

You both make very valid points.

The main thing I think to highlight in this case is the bloody fingerprint should have been visible and recorded (Would this be fair to say ?)

Because of what we know about Swann confirming Y7 & QI2 wrongly I think it important all his work is now peer reviewed.

He confirmed for CCRC that this belonged to the suspect and was in blood overstepping he expertise as he is not an erxpert in blood or substance analisis.

Graham hit the answer spot on, by saying if there was a bloody print it would have been visible therefore no need to spray any substances at-all.

Should it also have been photographed and recorded which seems to be absent from this case ?

Please take it from me that experts cannot any longer say if it is blood let alone the blood of the victim, however their reports are available on the link above.

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Re: Ninhydrin Prints Developing?

Post by bficken » Thu May 17, 2012 8:14 am

Amy -

To add to your list of answers, I also know of a case in which a ninhydrin-developed paper went to court and was found to have a higher number of developed latents than it did when it was packaged after processing. That ninhydrin formula was methanol based. Unfortunately, I do not recall the length of time between chemical treatment and packaging, nor the length of time between packaging and court. I've read training materials that stated ninhydrin can take up to 5-7 days to fully develop (without the addition of heat and humidity). Of course, the trade off of waiting is that initially developed latents will begin to fade.

I think everyone knows that this is a risk with ninhydrin. My understanding is that it is up to each individual laboratory to determine the best method to deal with this issue. I encourage your lab to run some studies, decide on the appropriate amount of time to wait for ninhydrin to react, decide how to document the developed latents (i.e. do you photograph on the first and the last day of development, or just the last day, etc), and then add all of that to your procedures manual. At least that way you have something to tell a defense attorney in court. "Based on an internal validation study of ninhydrin, we determined..." Also think about finding some published studies to reference.

And in case you are also collecting info on what everyone else does - we use an HFE based ninhydrin, put treated items into a humidity chamber that is set to 70 degrees C and 70% relative humidity (time in chamber is dependent on development, we watch our test prints to determine this), photograph developed latents immediately, wait 24 hours and examine the item again, photograph any newly developed latents, and then proceed with the next chemical.

Hope that helps.

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