Monday, November 10, 2008

Gotcha

by Barbara D'Amato


Leicester University in the UK invented DNA fingerprinting in 1984. Now comes news that they will soon be able to predict the surname of a male suspect from blood, hair, saliva or semen found at a crime scene.

DNA on the Y [male] chromosome is passed down the male line. A study of 2,500 men showed that there was a twenty-four per cent likelihood of two men with the same last name having a common ancestor. However, if the last name was uncommon, the chance of a common ancestor was fifty per cent. With very uncommon names, the chance went as high as seventy per cent.

Sooooo—with a large enough database of Y chromosome DNA, a crime scene analyst will be able to send a hair to the lab and, in whatever time it takes, tell us “This hair is from a man named Fosdick.”

Mitochondrial DNA, mtDNA, is inherited from the mother. Both males and females inherit their mother’s, and the father’s is lost. If a person’s mtDNA mutations are the same as another’s, they have a common ancestor. Comparing a sample to the Cambridge Reference Sample identifies the maternal line. All humans today belong to one of only thirty-three haplogroups or clans, which are ethnically specific. In other words, the lab can look at your mtDNA and tell your ethnic makeup. There are even companies which will test your mtDNA and come with an ancestry portrait—for example Fosdick is 2 per cent East Asian, 10 percent Native American, and eighty-eight per cent European.

Since DNA already tells ethnicity and such things as genetic diseases and physical appearance – Fosdick has brown hair and salt-sensitive hypertension -- and mtDNA reveals ancestry, there will soon be nowhere to hide. As crime writers, until fairly recently we had only to keep our malefactor from leaving fingerprints if we didn’t want to catch him too quickly. More recently we had to deal with DNA, but of course that couldn’t be matched unless the police found the bad guy. Now from a smidgen of blood we know what he looks like. Soon we will know his name.

To the crime writer this is both a challenge and an opportunity, as PRESUMED INNOCENT used an earlier level of forensic analysis to befuddle the reader.

The bar has just been raised.

6 comments:

Jake Nantz said...

Yikes, I better put that st--...er, I mean 'my character' better put that stereo and plasma TV back.

Great (if frightening) info, Ms. D'Amato! Thank you for that!

Anonymous said...

perhaps it was an oversight, but you failed to state the obvious. that is, it was joseph wambaugh who celebrated the british breakthrough in dna sampling. it was his book, the blooding, that chronicled the case in england. it is a solid read and worthy of mention here.
gordon comstock

Anonymous said...

But what if a suspect is adopted??? You still need a history or story, which is why writers need not fear.

Can this be used to identify parents who gave kids up for adoption, or even sperm donors?? Now there's a story waiting to be written!

Barbara D'Amato said...

Thanks, jnantz, anonymous and kathryn. Yes, THE BLOODING chronicled the DNA breakthrough and is a good read. Kathryn, as far as I know, and I am no expert, this present technology could narrow down where to look for birth parents and sperm donors. It can't tell you where they live yet, but could certsinly confirm the i.d. if you had a possible person. As you say, there are stories waiting to be written.

Actually, I find the whole thing kind of scary.

Wilfred Bereswill said...

Advances in technology in general can cause crimewriters to do some soul searching.

At the climax of my first novel, my Protagonist is trying to prevent an event from happening. As I'm writing it, I have this explosive ending in mind and it dawns on me, shy doesn't she just pick up her cell phone and call.

I could have used the "no bars" excuse, but I thought that was cheating. It took me a week to come up with a very plausable reason. In the end it made for a solid finale.

I'm just hoping all those Bereswill males out there stay on the straight and narrow.

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