Blood transfusion - mistaken identity? - Tilted Forum Project Discussion Community

Nafter · 11-16-2003, 10:51 AM

Aight, i was discussing DNA tests with some friends, and came accross this idea, If a burgler was robbing a house and cut himself on glass, the DNA of the blood was taken and a match found, normally this would incriminate that person. What happens if that person has had a blood transfusion on the days preciding, wouldnt he have others DNA, possibly several other peoples DNA in his blood? This could lead to a case of mistaken identity and the wrong person arrested?
How long do blood cells last in a persons blood, and is this hypothetical situation possible? or have we overlooked some key factor?

thoughts anyone?

Silvy · 11-16-2003, 12:36 PM

I'm no expert here but some thoughts come to mind:

- DNA testing is not 100% accurate even in the best of times. As evidence it is presented as a percentage based accuracy. So other evidence (even circumstantial is needed).

- Being arrested comes before DNA tests (usually) so they'd have to have a suspicion(sp?) first. If the test fails, they'd probably check some background anyway.

- To be convicted for a crime you not only would need to be at the scene but you would also not be somewhere else. iow: it's likely that the donor has a perfect alibi.
(never mind the fact that the donor could live thousands of miles away...)

- Don't the DNA tests show 'weird' results if the blood has been contaminated?
- Are tests done more than once to make sure?

In general: it's possible, but not likely in my opinion.

lordjeebus · 11-16-2003, 12:46 PM

Blood cells last for about a month.

Assuming that a good quantity of the person's blood is not originally his, I would guess that the DNA test would come up as inconclusive.

Perhaps (I don't know how donated blood is tracked) the authorities could seek to find the source of his transfused blood, mix it with his, and compare that way.

More likely they wouldn't use the DNA as evidence.

The chances of accidently arresting the blood donor in the first place seem very low to me.

EDIT: Did some googling, they last about 4 months, not one.

krwlz · 11-16-2003, 12:58 PM

Also, most DNA tests out there simply eliminate suspects. Not nail it down to one person.

jay-g · 11-16-2003, 03:41 PM

If you think about it, the hosiptal where the suspect was born would know the blood type. Sooo.......

lordjeebus · 11-16-2003, 03:48 PM

Quote:

Originally posted by jay-g
If you think about it, the hosiptal where the suspect was born would know the blood type. Sooo.......

That's irrelevant though. The suspect would have received a blood transfusion of the same blood type. Hospitals don't keep DNA samples of babies.

MSD · 11-16-2003, 04:22 PM

Quote:

Originally posted by lordjeebus
That's irrelevant though. The suspect would have received a blood transfusion of the same blood type. Hospitals don't keep DNA samples of babies.

Transfusions would be of the same a/b/o type, but an rh+ person could recieve a sample of the same letter but rh-, or o-

I've asked this of a forensic scientist who visited our high school, and he said that either the transfused blood would not show up, or it would throw the results off enough that hair samples or a cheek scrape or similar tissue sample would be used.

Psivage · 11-16-2003, 04:47 PM

I always wondered about blood transfussion, I had a hell of lot of transfussion, through operations and such not. I keep thinking what is really me and what is really them. Does somebody's else blood change who you are. Ever since I was born I've had operation, so am I really me or somebody else.

lordjeebus · 11-16-2003, 04:52 PM

Quote:

Originally posted by Psivage
I always wondered about blood transfussion, I had a hell of lot of transfussion, through operations and such not. I keep thinking what is really me and what is really them. Does somebody's else blood change who you are. Ever since I was born I've had operation, so am I really me or somebody else.

I doubt it. That blood doesn't stay with you forever -- it's eventually replaced by blood of your own. And blood cells can't differentiate into other types of cells, so the genes in them aren't going to do anything to you.

clavus · 11-16-2003, 07:10 PM

I guess you'd call the mistake a "Type-O."

Reese · 11-17-2003, 06:18 AM

He would have different dna in him mixed with his and when they did the dna test they would find more than 1 persons dna. Since the DNA doesn't accuse someone unless they are already a suspect it's be near impossible for a donor to be found guilty.

Also, When they did find 10+ people's dna in the same drop of blood I would hope it would ring a bell that there's something fishy...

I'm not sayin it couldn't happen, but theres a better chance of winning the lottery 10 times in 10 days.

dnd · 11-17-2003, 03:23 PM

Quote:

Originally posted by clavus
I guess you'd call the mistake a "Type-O."

i can't believe i'm actually laughing out load at that!!!

txlovely · 11-18-2003, 05:05 PM

That was laugh out loud good... I can believe it. Simple humor - fast and slick. Gotta love it, Clavus.

11-16-2003, 10:51 AM	#1 (permalink)
Nafter Insane Location: The Eng	Blood transfusion - mistaken identity? Aight, i was discussing DNA tests with some friends, and came accross this idea, If a burgler was robbing a house and cut himself on glass, the DNA of the blood was taken and a match found, normally this would incriminate that person. What happens if that person has had a blood transfusion on the days preciding, wouldnt he have others DNA, possibly several other peoples DNA in his blood? This could lead to a case of mistaken identity and the wrong person arrested? How long do blood cells last in a persons blood, and is this hypothetical situation possible? or have we overlooked some key factor? thoughts anyone?

11-16-2003, 12:36 PM	#2 (permalink)
Silvy paranoid Location: The Netherlands	I'm no expert here but some thoughts come to mind: - DNA testing is not 100% accurate even in the best of times. As evidence it is presented as a percentage based accuracy. So other evidence (even circumstantial is needed). - Being arrested comes before DNA tests (usually) so they'd have to have a suspicion(sp?) first. If the test fails, they'd probably check some background anyway. - To be convicted for a crime you not only would need to be at the scene but you would also not be somewhere else. iow: it's likely that the donor has a perfect alibi. (never mind the fact that the donor could live thousands of miles away...) - Don't the DNA tests show 'weird' results if the blood has been contaminated? - Are tests done more than once to make sure? In general: it's possible, but not likely in my opinion. __________________ "Do not kill. Do not rape. Do not steal. These are principles which every man of every faith can embrace. " - Murphy MacManus (Boondock Saints)

11-16-2003, 12:46 PM	#3 (permalink)
lordjeebus ‚±‚Ìˆó˜U‚ª–Ú‚É“ü‚ç‚Ê‚© Location: College	Blood cells last for about a month. Assuming that a good quantity of the person's blood is not originally his, I would guess that the DNA test would come up as inconclusive. Perhaps (I don't know how donated blood is tracked) the authorities could seek to find the source of his transfused blood, mix it with his, and compare that way. More likely they wouldn't use the DNA as evidence. The chances of accidently arresting the blood donor in the first place seem very low to me. EDIT: Did some googling, they last about 4 months, not one. Last edited by lordjeebus; 11-16-2003 at 12:48 PM..

11-16-2003, 07:10 PM	#10 (permalink)
clavus pow! Location: NorCal	I guess you'd call the mistake a "Type-O." __________________ Ass, gas or grass. Nobody rides for free.

11-17-2003, 06:18 AM	#11 (permalink)
Reese Delicious	He would have different dna in him mixed with his and when they did the dna test they would find more than 1 persons dna. Since the DNA doesn't accuse someone unless they are already a suspect it's be near impossible for a donor to be found guilty. Also, When they did find 10+ people's dna in the same drop of blood I would hope it would ring a bell that there's something fishy... I'm not sayin it couldn't happen, but theres a better chance of winning the lottery 10 times in 10 days. __________________ “It is better to be rich and healthy than poor and sick” - Dave Barry

11-16-2003, 12:58 PM	#4 (permalink)
krwlz Fledgling Dead Head Location: Clarkson U.	Also, most DNA tests out there simply eliminate suspects. Not nail it down to one person.

11-16-2003, 03:41 PM	#5 (permalink)
jay-g Addict	If you think about it, the hosiptal where the suspect was born would know the blood type. Sooo.......

11-16-2003, 04:47 PM	#8 (permalink)
Psivage Psycho	I always wondered about blood transfussion, I had a hell of lot of transfussion, through operations and such not. I keep thinking what is really me and what is really them. Does somebody's else blood change who you are. Ever since I was born I've had operation, so am I really me or somebody else.

11-18-2003, 05:05 PM	#13 (permalink)
txlovely Insane Location: ...We have a problem.	That was laugh out loud good... I can believe it. Simple humor - fast and slick. Gotta love it, Clavus. __________________ Cruel words erode self-esteem like the ocean eats away the shore.