One For The Criminologists

[rocketpost1]

Just a hypothesis. A man has a blood transfusion and commits a murder say within a few days. If blood is found at the crime scene, it is possible that a DNA profile could point to the blood donor rather than the recipient ?.

[charlieuniform3]

I thought if you had a blood donation it had to match your original blood?

[ummmm]

No it doesn't. I'm B but I can accept blood from O.

[sherrardk]

I'd be wondering how someone who was poorly enough to have a blood transfusion was up and about committing a murder a couple of days later.

[nungate]

I think the DNA is altered if the man has had a transplant of bone marrow or something - something of this sort happened in a crime drama, as usual I can't remember the exact details!

[237SJ]

Red blood cells don`t carry DNA and most transfusions have red blood cells, not white.

[jim360]

See here:

http://www.straightdope.com/columns/read/1418/does-a-blood-donation-mess-up-dna-evidence

[rocketpost1]

Thanks Jim360. That's the perfect explanation. Thanks also to 237SJ for the information regarding red blood cells which I didn't know.