Showing posts with label DNA. Show all posts
Showing posts with label DNA. Show all posts

Friday, February 27, 2009

NPR CLAIMS Regarding National Academy of Science Report on Forensics

The committee found there isn't enough research behind many forensic techniques to show how accurate and reliable they are.

It also says forensic labs are underfunded and understaffed, and there's no mandatory certification to ensure quality.

It says forensic analysts' court testimony commonly refers to evidence being a "match" or "consistent with" a suspect, even though no forensic method except for DNA analysis "has been rigorously shown to have the capacity to consistently, and with a high degree of certainty, demonstrate a connection between evidence and a specific individual or source."


While autosomal DNA has passed a Daubert test on whether it is scientific, it receives very little needed review that would show it is not the "gold standard" of forensics.

In Illinois they found 903 pairs of profiles of separate individuals matching at nine or more loci in a database of about 220,000.

In Maryland, in a database of fewer than 30,000 profiles, 32 pairs matched at nine or more loci. Three of those pairs were identical at 13 out of 13 loci.


RECOMMENDED READING:
The danger of DNA: It isn't perfect
The verdict is out on DNA profiles
Top lab repeatedly botched DNA tests
Crime labs finding questionable DNA matches:
FBI tries to keep national database away from lawyers

Monday, February 9, 2009

Magic Trunks and the DNA "Gold Standard"

For those of you that have followed the Anthony case, what a magical trunk! It has all kinds of vapors and DNA that prove Caylee is dead. Not that that can be scientifically proven.

No DNA sample alone can prove the donor is dead. Nor can any vapor. If it smelled dead, likely an investigator had a bad meal as the same gases can be involved.

As far as googling for ways to create chlorophorm or breaking necks, that could have been done by the kidnapper(s) .

Supposing that a death HAS occured, that eliminates the aggravated murder because the chlorophorm causes the heart to stop while unconcious.

If you mix chlorine (bleach) and acetone (nail polish remover) or isopropal alcohol (rubbing alcohol) this can accidently produce chlorophorm. Obviously, a child can do this - or an adult by accident.

The more I read these articles, the less I trust the AP, the media who copy them, or the prosecutor for eliminating the alternative hypothesis.

The DNA in this case was a "high resolution" test of the mitochondrial DNA. I have had this test. I have over 278 matches at http://www.familytreedna.com/ .

That was part of a full genome sequence (FGS) of my mitochondrial DNA, which I have no matches to in a database of over 80238. I have a copy of the report. Their DNA test is of less than 1319 base pairs. My test was of 16,570 base pairs. (I have one insertion more, which is not rare.) This means my FGS has 12 times more resolution than the FBI test.

I read a Certificate of Analysis from the Virgina Deparment of Forensic Analysis which used 16 markers instead of the 13 that the FBI does for more resolution. The technition said:

This information is provided only as an investigative lead, and any possible connection or involvement of this individual to this case must be determined through futher investigation.

SO, these tests are not the end all in investigations. They add to the proponderence of evidence, but they do not make a case "beyond a reasonable doubt."

Whenever I find that DNA testing is being done, I want to know:

What were the DNA tests that were run?

In the CODIS database of Maryland , of fewer than 30,000 profiles, 32 pairs matched at nine or more loci. Three of those pairs were "perfect" matches, identical at 13 out of 13 loci. Experts say they most likely are duplicates or belong to identical twins or brothers, but they did not establish that.

A study of the Arizona CODIS database carried out in 2005 showed that approximately 1 in every 228 profiles in the database matched another profile in the database at nine or more loci, that approximately 1 in every 1,489 profiles matched at 10 loci, 1 in 16,374 profiles matched at 11 loci, and 1 in 32,747 matched at 12 loci.

In a case against a Murillo-Sosa, a jury was told the match was 5 of 13. They had to say he was not guilty. SO, what kind of matches are they making? How about doing it right the first time and take the time to get a FULL DNA testing of Y chromosome DNA and mitochondrial DNA, as well as autosomal (CODIS) DNA?

Is it a mitochondrial DNA test which matches everyone who descended from the same maternal ancestor in the last 20 generations as THE DEFENDENT(S) ? Is it just a "high resolution test" which the FBI performs or a real full genome sequencing of the mitochondrial DNA?

Is it a Y Chromosome test which matches everyone who has the same paternal lineage for the past 400 years? If so, is it 12 markers, which could be one to fifty percent of the population, or is it a 67 marker test that can pin it down to a surname?

There may be a way to combine all of these that will resolve the identity to one person, but is what they have beyond a reasonable doubt unless they do FULL testing?