The Out-Lawyer's Blog

Maybe this IS Rocket Science …
Print Version Link: http://jaygaskill.com/SophistryTrap.htm
Beware Defense Sophistry

Wired Magazine’s reporter, David Kravets, and other intelligent commentators, have repeated the erroneous idea the OPD’s criminalist failed to definitively identify Nina’s blood on the post in the front doorway of the Exeter house.  I’m reminded – painfully – how tricky DNA typing can seem to a lay jury (thinking here of the O. J.  miscarriage of justice because a jury in effect rejected DNA evidence it failed to understand).

“OAKLAND, California -- A forensic specialist testified here Wednesday she had made a mistake when analyzing blood found in the house where Hans Reiser's wife was last seen.
The fragments of blood, the scientist testified Tuesday, contained DNA from the Linux guru and his wife, Nina Reiser. The authorities discovered it on a pillar in an entryway in the Oakland hills house two weeks after the 31-year-old woman went missing Sept. 3, 2006.
But on Wednesday, the scientist testified on cross examination that errors she made meant it was unclear whether there was two sources of blood -- meaning it could be the wife's or the husband's -- or blood from both of them. She testified she was not "100 percent certain" whose blood was on the pillar.

This problem has been conflated to the false assertion that the DNA evidence has failed to identify Hans’ and Nina’s blood on the entryway post.  Not so.
This incident shows how easily defense cross examination can mislead highly intelligent observers, and how DA Paul Hora completely missed the opportunity, on redirect, to clear up the matter. 
The forensic “error” , here, was in the failure to take two swabs from the post, so that OPD’s expert witness was left uncertain whether the blood was from two distinct smears, possibly overlapping or just one.  The takeaway point, however, was that, beyond any reasonable doubt, Hans’s blood AND Nina’s blood were BOTH on the post.
JBG