For the Defense - Vol. 7, Issue 3 - 10

* CASE 4C: The defendant was in a rental car.
Although rental cars are generally cleaned between
rentals, the degree and thoroughness can vary. With
this scenario, the idea of secondary transfer from
the car is unlikely unless the defendant has had the
vehicle for several days and has had extended time in
the vehicle. What is more likely is secondary transfer
from a personal item of the defendant, such as a
shirt, shoes, napkin, or other item in the vehicle. The
gun could have been introduced by the passenger or
left behind by a previous customer. Knowing what
other items were in the vehicle in close proximity to
the gun would be helpful in determining if secondary
transfer is a possibility, so ask for photos and/or video
footage.
CASE 5: COLLECTOR-MEDIATED TRANSFER
Even with all of these cases, studies, and scenarios,
there
is
still
another
possibility
to
consider:
Contamination because of the forensic process itself.
* CASE 5A: The Phantom of Heilbronn.
In the 2000s, a female DNA profile led police
agencies throughout Europe on a merry chase.20
Her DNA linked over 40 cases, ranging from home
invasions and burglaries to triple homicide. Dubbed
" The Phantom of Heilbronn, " she was ultimately
discovered to be a worker at the factory that
manufactured the swabs that were used in all the
cases.
* CASE 5B: Phantoms in the mortuary.
Studies have shown that DNA contamination can
also occur at autopsy.21, 22
given the quantity of DNA available during this
process, thus making trace contamination easier.
* CASE 5C: The defendant's DNA was detected on a
weapon.
In one case, the defendant's DNA was detected on
a gun. A review of the laboratory's notes revealed
that the examiner observed brown stains on the gun
without performing any tests to identify it. A review
of the officer's body-worn camera footage showed
him and a fellow officer chasing the defendant
down a darkened street at night, and that there was
a metallic bang as he ran past some metal garbage
cans. The defendant turned right, which was a blind
alley. The officers " subdued " the defendant and
" escorted " him back to their cruiser. As they passed
the row of garbage cans, one officer stopped to
10 For The Defense l Vol. 7, Issue 3
This is of little surprise,
investigate. The footage showed the officer's hand,
wearing a blue nitrile glove covered in blood, holding
a gun. When the forensic scientist was shown the
video, she could not refute that the brown stains
could be the defendant's blood, transferred by the
officer.
While extreme, the transfer of DNA can be far more
subtle. All it would take is a pat-down to contaminate
the officer's hands or gloves with the defendant's
DNA, which can then transfer the defendant's skin
cells to the next object that the officer touches. Even
more subtle:
The officer touches a contaminated
object or surface, like clothing or the driver's seat,
and then touches an item of evidence.
* CASE 5D:
The defendant's DNA was detected
on... something.
In one study, various contact surfaces were
sampled throughout the laboratory to test for latent
DNA.23
A DNA profile was detected on a magnifying
lamp, which was traced back to a case that had
been examined in that room three months prior.
It is believed that the analyst, while examining an
item, touched the lamp with contaminated gloves.
It would have been possible, then, for this DNA to
contaminate a fresh pair of gloves, which could then
contaminate the next item of evidence. In another
study, it wasn't the gloves, but the powders and
brushes used by latent print examiners.24
For the Defense - Vol. 7, Issue 3

Table of Contents for the Digital Edition of For the Defense - Vol. 7, Issue 3
