Author Forensic Question: DNA and Donated Blood

Today, I'm posting a forensic medical question I had for Amryn Cross.

Jordyn Asks:

Can you tell if blood from a crime scene is from a donated pint of blood? If so, how?

Amryn Says:

You can actually tell the difference. A donated pint of blood will only have red blood cells and not the other components of blood (white blood cells, platelets, etc.). When the DNA from the donated blood is tested, the scientist would probably think it odd that they got little to no DNA yield (red blood cells don't have nuclear DNA). They might chalk it up to degraded blood, or they might look at it under the microscope and find only RBC, which should make them suspicious. But probably the first indicator is that the blood at the crime scene would not clot if it were from a donated unit. The investigator may or may not pick up on that, but a crime scene tech probably would.

Jordyn Asks:

What about a pint of whole blood? Would it still be the same? Would small amounts of dry blood give DNA?

Amryn Says:

Whole blood would give DNA results but wouldn't clot, so that would be something they would have to pick up on at the crime scene. If it was suspected and they wanted it verified, tests could be done for the preservatives in the bag.

Yes, if they were just droplets, they would still dry over time. And as long as it's whole blood, it will give lots of DNA.

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Amryn Cross is a full-time forensic scientist and author of romantic suspense novels. Her first novel, Learning to Die, will be released in September. In her spare time, she enjoys college football, reading, watching movies, and researching her next novel. You can connect with Amryn via her website, Twitter andFacebook.