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Author Topic: Blood Forensics Question - Can You Help?  (Read 8259 times)

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aspiringhopeful

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Blood Forensics Question - Can You Help?
« on: May 04, 2013, 01:07:14 PM »

*quick disclaimer*

I've got 3 tales in the works and have become blocked on all of them, hitting a wall on some forensics. My first inclination was to call up local police station and or clinic and ask my questions in a general sense but figure I'll either get the run around, vague answers, or worse when I'm feeling super paranoid, they'll suspect I'm planning a crime and next thing I know, FBI's at my door (and god knows if they confiscated my computer I'm so going to the slammer given all the research on death and murder I've done!). I'll make 3 topics for each one so as to not overload on any one thing.

And I am brand new, was looking around for what seemed like truly helpful, friendly forums to ask my questions, and who might cut me a little slack for jumping in to ask without being part of the community just yet. Hopefully it won't count against me too much, huh? Pretty please? :)

/end disclaimer

Premise: jerkish husband unwittingly finds himself charged with homicide in the death of his wife who's gone missing, and circumstances are such that even though his alibi was legit, he can't prove it so it looks really bad for him. This will have many other elements but this particular thread in the story is where I need to get the research pat because the key piece of evidence will be a cleaned area that's picked up with luminol, positive for blood, connected to the missing wife so it looks for all intents and purposes that an assault/murder took place in that spot of their home and was cleaned up.

The catch I had in mind, though not settled on it, is that the wife was going through nursing school at some point years previous but stopped working when she got married. She was doing "x" test (need suggestions) in which she was drawing her own blood via a syringe. I need a simple procedure corrected - the scenario is she draws blood and stores it still in the syringe in the fridge for a few hours. When she removes it later, still cold, she mishandles it and squirts it all over the floor and fridge door, screwing up her "x test" in progress. She cleans it up but misses a couple spots and it's this scenario that forensics discover and conclude the husband killed her in the kitchen and cleaned up the mess, disposed of the body.

The overall premise for the husband character is to stack the deck against him at every turn, where he not only looks guilty in circumstance, all sorts of forensic and other evidence points to him, even though fundamentally it's incorrect and he's innocent, and it's his struggle through the overall story to clear his name when it would probably crush most ordinary citizens, through a methodical process that shows how clear cut forensic evidence can still be horrifyingly wrong.

The question is regarding the wife doing her test. What would be a reasonable explanation for someone to draw their own blood and would that be logical to put the whole syringe in the fridge a few hours, or would it need to be transferred into some other thing, and if so, what kind of thing, and how would that be mishandled so it ends up on the floor?

Part 2 of the question, since it'd been stored a few hours in the fridge, then ends up all over the floor, cleaned up, and a couple spots are found - is there something in the forensic sense that can tell the difference between blood spilled through a natural injury and blood that was chilled awhile - would this be the area it falls apart, when investigators get results from the lab on blood evidence and find out they can tell it was chilled blood and didn't come out of an injury? On the one hand, it'd be nice to use this to ultimately clear the husband, but then the entire scenario falls apart if they can figure that out in a standard lab work right off the bat.

What I need is a perfectly reasonable scenario for the wife to draw blood and store in fridge, and then after the mishandling and cleaning, the stuff missed works against husband in suspected homicide. I'm certainly open to other suggestions, this is just the one that jumped in my head and won't leave. I don't deal in blood so have no idea if this is something that can be detected easily or at all.

Any feedback is much appreciated, and I look forward to thread hopping and getting more involved.

Thanks in advance to whoever takes time to answer!
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Old Bill

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Re: Blood Forensics Question - Can You Help?
« Reply #1 on: May 05, 2013, 11:06:20 AM »

Welcome aspiringhopeful.  Glad to see you participating in this forum.  You have an interesting idea and I hope some of our members have answers for you.  I don't have a good answer but what I suggest to newcomers is not to be afraid of approaching reliable local sources for information.  Done the right way, you will find professionals happy to help.  The right way:  start with a phone call to the agency you want to get info from to find out who to talk with...public relations office, director, chief, etc.  Follow up with a letter explaining your circumstances if necessary and be prepared to either share some of your previous work or work-in-progress (WIP) to show you are a serious writer and not some whack-job.  Be professional at all times and respect your interviewee's position.  Not everyone will or can give out information due to dept regs or privacy restrictions.  Offering to give acknowledgement is a nice gesture also.

Hope this helps and good luck with your project.

Old Bill
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mcCarthy88

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Re: Blood Forensics Question - Can You Help?
« Reply #2 on: May 05, 2013, 07:25:23 PM »

Hello there aspiringhopeful

I'm a med student so I may be able to help you out.

Nursing students (like us) practice taking blood from one another and placing IVs all the time. If the IV falls out or isn't placed correctly, then blood could easily spill out in the scenario you describe, although it's more of a trickle and likely wouldn't show up on luminol. However, I can't think of any reason a student would take blood, store it in the fridge, and then take it out - and even then, it's almost impossible to accidentally discharge the contents of a syringe in the manner you suggest. Also, by the time an old blood sample is discovered by luminol, very little forensic analysis other than typing and DNA can still be done.

However, I do think I have a potential solution to your issue. If I'm right, you want a scenario where there's a logical explanation for your nurse character's blood to have been cleaned off a wall and then a way for her husband to prove that this was innocent?

Some nurses (especially those who work in the ICU) perform something called an 'art stab'. This involves taking blood from the artery in the wrist. If this goes wrong, it can produce A LOT of blood, that would mimic the blood-spatter pattern from a stab wound. Say your nurse character has a fellow student who's practicing an arterial stab on her at the house. This goes wrong, and the blood ends up on the wall. After the murder, this is found with luminol, and the investigators don't believe your husband explaining the blood, telling the story about his wife and her student friend. If he can track down the friend (who's maybe moved away to find work) then he has a witness who can prove his innocence...

Hope that helps in some way,

McCarthy.

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aspiringhopeful

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Re: Blood Forensics Question - Can You Help?
« Reply #3 on: May 07, 2013, 01:48:34 AM »

Thanks :)

That's helpful and the suggestion is possible. What is the purpose of an art stab, as in what kind of scenario is it done? I've never heard of it. Is it just practicing the art of injection or is there more to it?

Just for clarification purposes, if the blood was drawn via the syringe and a full quantity of it, similar to the amount used for taking blood samples I guess, and it was stored at all, and later spilled onto the floor, cleaned up, are you saying it isn't apt to show up in a luminol or alt lighting test, or that there's no way to determine it was ever blood?

Same scenario, is there anything about syringe drawn refrigerated blood that makes it forensically different than injury spilled blood, whether it's contaminated with cleaning products or not?

I'd prefer a scenario where blood spilled in a relatively large, harmless way can be mistaken for potential homicide. If all else fails, I might just have her step on broken glass and bleed everywhere early on, but then it's back to how he'd figure that out if he's not present. Maybe she could just tell him it happened early in the story and he's forgotten all about it by the time it hits the fan. Just looking for something a little cooler forensically :D

I appreciate your feedback. After posting I realized so many threads haven't been active in a year or two so figured maybe this forum was............RIP :P
« Last Edit: May 07, 2013, 01:59:44 AM by aspiringhopeful »
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mcCarthy88

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Re: Blood Forensics Question - Can You Help?
« Reply #4 on: May 07, 2013, 05:09:52 AM »

Hey - I'll try and answer your questions as best I can one by one.

1. An arterial stab (the abbreviation 'art stab' stands for arterial) is done when you need to take blood from an artery. Usually when you take blood, you do it through an IV from a vein. Sometimes really sick patients need to have the composition of their arterial blood analysed (which is different to venous blood), which is why it's often done by ICU nurses. Obviously because you're puncturing an artery not a vein it's more dangerous, and there will be a lot more bleeding if you get it wrong.

2. When you normally take blood, you only take a little amount (about 5 cc's). If that got spilled, it would be picked up on luminol for sure, but only DNA testing and typing could probably be performed. You couldn't, for instance, pick up a drug which had been in the person's system, or do other more complex forensic tests.

3. As far as I know, there's nothing forensically different about blood from injury than blood taken 'medically'. You're still 'injuring' the patient when you puncture them with a needle, and even then the chemicals released when a wound is made are in concentrations too small to detect by any test.


As I said earlier, having a friend practice an arterial stab on her friend and get it wrong (this might be by accidentally knocking the needle out too early, for instance) would cause a lot of blood to spurt out at high pressure. This would create the blood-spatter pattern seen in, say, a stab wound. A forensic blood-spatter analyst may reasonably conclude that this was an indication of murder, where as something like stepping on glass would produce a rather different pattern, as the blood would gush and pool rather than spurting.

Now here's the forensically cool part! (I did a little research at the pathology department...) There's a test known as "temporal RNA-PCR" which can determine the age of a bloodstain. It's not normally performed, as it's complicated and expensive, but it would provide a way for your hero to clear his name. Say the murder happened a month ago, and your character's wife had her accident with the arterial stab five years ago. A temporal RNA-PCR test would reveal that the bloodstain was from over a year ago (it can't really be more specific further back than that), which would clear his name. Here's a link to a document explaining temporal RNA-PCR for you: https://www.ncjrs.gov/pdffiles1/nij/grants/213892.pdf

(That's from a scientific journal, so feel free to reply/message me if you want it explained in layman's terms)

Hope that helps
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aspiringhopeful

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Re: Blood Forensics Question - Can You Help?
« Reply #5 on: May 15, 2013, 04:59:12 PM »

Awesome, thanks so much for that!

I will probably take you up on it if you're sure you don't mind.

If you could suggest some layman reads on blood work forensics that would be fantastic. I've got two areas I do need a crash course research in - the blood evidence and death penalty cases since he would ultimately be given the death penalty and have to clear this up while incarcerated, which of course makes it far more challenging.

As originally mentioned, I'd love to find a LEO somewhere who could give me feedback but I'm still a bit leery about just asking and then having to clear my name minority report style - some of them get a little overzealous and it's just a story :P

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Dave Freas

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Re: Blood Forensics Question - Can You Help?
« Reply #6 on: May 15, 2013, 09:39:36 PM »

Hi, Aspiringhopeful, and welcome to MWF.

Get a copy of Lee Lofland's Police Procedure And Investigation.  Lee's a retired police officer and his book is a great resource for anything relating to the police.

Hope this helps.

Dave
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KarensaK

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Re: Blood Forensics Question - Can You Help?
« Reply #7 on: August 23, 2013, 04:15:32 PM »

Thanks, Dave!

I picked up Forensics and Fiction  (DP Lyle), which helped tremendously in how to set that up. The problem with the explanation from that book is the answer was provided based on the premise the blood would be visible and could be tested for age.

In my scenario, collected blood would be spilled to fake a murder, but then cleaned up with bleach and hydrogen peroxide solution to destroy and/or contaminate it as much as possible. The idea being that the location will reek of a good scrubbing and upon investigation with an alternate light source and luminol would show up as large streaks, smears and scrub circles and in such a quantity to suggest the victim couldn't have survived that sort of blood loss - the purpose being to support a murder charge and arrest, and subsequent conviction without a body.

My main question in that respect would be if it was possible for such luminol and presumptive tests for blood to be able to identify it as blood (which is desired for the plot) but unable to detect that it was stored and planted.

Any ideas?
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