Category Archives: DNA

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High Court Acquits Man in a Rape Case Based on New DNA Evidence

From the Japan Times:

High court acquits man in 2012 teenage rape case based on DNA test

Kyodo

A high court has acquitted a man charged with raping a teenage girl in 2012, overturning a lower court ruling that gave him a four-year prison term.

The Fukuoka High Court’s Miyazaki branch issued a ruling Tuesday saying that a fresh DNA analysis did not prove that the 23-year-old man from the city of Kagoshima was the culprit.

It also said the police may have hidden the result of an earlier DNA analysis that did not match that of the defendant.

“In determining the defendant to be the criminal, semen (found in the victim’s body) should be that of the defendant. But the DNA analysis (conducted during the appeal trial) did not support her arguments,” presiding Judge Makoto Okada said.

In the DNA examination conducted by the Kagoshima Prefectural Police, the quantity of the semen found inside the body of the 17-year-old victim was reportedly too small for analysis.

The man’s lawyers had requested a fresh DNA analysis during the appeal trial, which showed the DNA did not match his. The high court said the result “was credible.”

The court acknowledged the defendant’s release from prison last March after the DNA test was conducted.

Okada was also critical of the staff in the police crime lab, who had disposed of all the used DNA solution and the memo that recorded the analysis process.

“The possibility cannot be ruled out that (the police decided to say that an) analysis was impossible because a different person’s DNA was detected, reflecting investigators’ intentions,” he said.

Okada also criticized prosecutors for asking experts to conduct another DNA analysis without notifying the court and the defense counsel.

“It can be suspected they intended to disclose the results only in the case that the outcome turned out to be favorable for them,” he said.

Kazunori Nakada, deputy chief prosecutor of the Fukuoka High Court Public Prosecutor’s Office, said it is “deplorable” that the court dismissed their arguments and that it will “deal appropriately” with the ruling after checking the content thoroughly.

The man, who requested his name be withheld, told reporters he was able to make it through the difficult period because of “the support of my family.”

“All I can say is that I’m happy,” he said, with tears in his eyes.

The Kagoshima District Court ruled in 2014 that DNA evidence detected from the victim’s breast was from the defendant. It also said the existence of semen, although unable to be analyzed, backed her accusations.

The man was indicted for allegedly assaulting the 17-year-old in an entertainment district in the city of Kagoshima in October 2012.

The man had said he had “no memory because I was drunk” and had insisted he was not guilty.

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Let’s Be Clear About DNA

The National Academy of Science’s landmark report, Strengthening Forensic Science in the United States, A Path Forward, states on page 7 that (nuclear) DNA is the only forensic method “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.”

This is, in fact, a true statement, with some important caveats. Nuclear DNA evidence is unequivocal, provided:

1)  There is a single DNA profile present in the sample.

2)  A sufficient quantity of genetic material is present in the sample

3)  The genetic material in the sample is not too degraded.

4)  It’s clear how the evidence arrived at the crime scene.

5)  The testing lab makes no errors in its analysis.

6) The sample of genetic material is from a primary transfer, not secondary or tertiary. (Deposited directly by the person indicated by the DNA profile.)

I won’t belabor you with the details of electropherograms, relative fluorescence units, molecular weights, loci, alleles, detection thresholds, or stochastic thresholds. I’m guessing your eyes would just glaze over.

But be aware. For cases in which the biological sample is a mixture of DNA profiles, or if the sample doesn’t contain sufficient genetic material, or if the sample is degraded, you get into the area in which the analyst has to start making judgement calls. And this puts things right back in the same boat with all the other forensic pattern matching evidence – fingerprints, hair and fiber analysis, ballistics & toolmarks, shoe prints, tire tracks, and bite marks – that rely solely upon the individual analyst’s training, knowledge, experience, judgement, … and cognitive biases. A good example of this would be the Amanda Knox case in Italy. You can see our earlier post about this case here, which goes into more of the detail of DNA analysis (including secondary and tertiary transfer).

Please maintain awareness – DNA is trickier than you might think. Just because someone says they have “DNA evidence,” doesn’t mean it’s a ‘slam dunk.’ You really have to dig into the details; and as always, “the devil’s in the details.” The DNA testing lab should provide a “probability of occurrence” statistic which reflects consideration of all of the above provisions. And keep in mind that the lab won’t be able to tell you if they made any errors in their analysis.

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Amanda Knox – The Period at the End of the Sentence.

Italy’s Court of Cassation has issued a final, formal opinion on the resolution of the Amanda Knox case.

It is a resounding exoneration of Knox and Sollecito, and a scathing indictment of a sloppy, inadequate, hastily contrived prosecution case.

See the ABC News story here.

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