Mystery Writers Forum
Life and Death => Police Procedures => Topic started by: NataliaChelenekov on February 09, 2015, 11:35:05 AM
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I have a question regarding proper police procedure when collecting evidence at a crime scene.
In my scenario a knife is found at a crime scene. Its blade is somewhat bent. The police collect and tag the knife. Sometime between the time the police collect the knife and the time the knife is sent to a crime lab for DNA and fingerprint analysis the blade is straightened.
Is straightening the knife contrary to proper police procedure protocol? Can straightening the knife destroy fingerprint and trace DNA evidence if it requires enough force such that it needs to be gripped with 2 hands to straighten the blade?
Thank you for any responses! :) Natalia
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I would have thought straightening the blade would be tantamount to tampering with the evidence. The fact that it's bent is most likely relevant to the case.
Keep in mind too that depending on the type of knife, it may not be possible to bend it without it snapping.
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Before the knife was collected as evidence, it would be photographed where it was found (and possibly fingerprinted). Then it would be placed in a bag, sealed, and the crime scene tech who collected it would sign his name on the seal, It would be recorded as 'Knife, 6-inch, bent blade, bloodstained' on the list of evidence gathered at the scene.
Yes, straightening the blade would be contrary to proper procedure, and when a technician at the crime scene lab went to process it for fingerprints, etc., he would note that the blade had been straightened - which may cause it to be excluded as evidence in the trial.
Straightening it may smear any fingerprints on the knife and could possibly contaminate any DNA - if it was done barehanded.
However, straightening the blade opens all sorts of possibilities. Did a cop or evidence tech do it? Why? Was it accidental or done to contaminate the evidence to hide who committed the crime or to get it thrown out as evidence?
Hope this helps.
Dave
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Very helpful guys. Thank you very much.
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Dave nailed it, Natalia. But to go further, consider the "Chain of Custody". Evidence is not just left around for anybody to access. The technician or detective that finds it would seal it and keep it in his/her custody until it is placed into the Property Office or delivered to the Lab, so only certain people would have the ability to tamper with it. And when I say "delivered" to the Lab, just that...delivered by the person who found or sealed it up. Any tampering would/should be discovered at any step along the way. As a former CSI, it was sometimes a chore keeping the unwitting officer/detective from handling the evidence. Our rule was, "You touch it, you own it."
Good luck with your story.
Old Bill
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Thank you Old Bill. You all are very helpful. I love this forum.