Thursday, March 26, 2009

DNA as Pixie Dust

For many months police in Germany and other parts of Europe have been searching for the "phantom of Heilbronn." See my earlier post, A Malicious Fairy Princess Spreading Spreading Pixie Dust Laced with DNA over European Crime Scenes? (May 14, 2008). This "woman without a face," DNA tests showed, had committed six different murders and also other crimes in various towns in Germany and Europe. A reward of 300,000 Euros was offered for clues to the identity of this female miscreant.

Oops. Yes, the crimes were committed. But the thesis that one evil woman committed all of them was, it turns out, very, very probably false. See "Eine sehr peinliche Geschichte," Spiegel Online (March 26, 2009).

What led to this snafu?

DNA.

More precisely, unsanitary packing procedures during the manufacturing process, perhaps.

The Spiegel story (in very rough translation) tells us:
It now appears that the chances of finding the trail of the mysterious suspect are slimmer than ever before -- because she apparently doesn't exist. According state's attorney Heilbronn, the Baden-Wuerttenberg Office of Criminal Affairs is now investigating whether the cotton swabs ["Q-tips"] that investigators used to collect DNA samples [at crime scenes] had already been contaminated with DNA and had thus led investigators on a false trail.

According to a report in Stern.de, the matter involves a packager [a packer, an employee] who worked for the manufacturer of the swabs that were used [at the crime scenes]. According to this report, the swabs were, to be sure, sterilized. But, according to Christian Rueff of the University of Zurich, such sterilization of the swabs does not affect contamination of the swabs with DNA by cells of the human body. [PT: The employee, I presume, held the cotton swabs in her hands when putting them into boxes or other containers.] The manufacturer delivered cotton swabs to various places in Germany and and also in France and Austria.
The article then proceeds to describe what led some observers to believe that the phantom woman might not in fact exist. One general problem was the large number of crimes -- 40 -- that the "phantom" supposedly committed in, supposedly, widely dispersed locations in Europe. Another hint that something might be amiss was that the supposed perpetrator supposedly began committing the crimes in 1993. But the immediate reason for doubt that a single woman committed the 40 or so crimes was the discovery that swabs of documents owned by a person who died in a fire had DNA that matched the DNA of the "phantom" -- which, an official proclaimed, "really could not be."

An official at the state prosecutor's office stated it was even possible that the cotton in the cotton swabs used in the police investigations was contaminated with DNA when it was plucked from the plant.


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My thanks to Lothar Philipps for alerting me to this story.


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Clarification: The corpse found in the fire apparently was never thought to be the corpse of the suspected culprit. The testing of the documents the dead person had owned aroused suspicion because the second time the documents were tested no matching DNA was found. See "'DNA bungle' haunts German police," BBC News (March 26, 2009).


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