One day after a crime scene investigator told jury members that no DNA
evidence could be found to link Dustin McCowan to items found near the body
of murder victim Amanda Bach, an expert with the Federal Bureau of
Investigation gave similar testimony.
The expert also said, however, that there are possible factors out there
that could prevent DNA from showing up.
Called to the stand was Heather LaSalle, a Forensic Examiner for the Nuclear
DNA Unit of the FBI, who said her lab processed 19 items for DNA profiles in
the case. The items were sealed and sent by officers of the Porter County
LaSalle said that when an item has DNA from a number of major and minor
contributors, the FBI calls the composite a “mixture.”
Chief Prosecuting Attorney Matt Frost asked LaSalle in direct examination to
speak about the stain found on the orange shirt recovered on the tracks of
the Canadian National railroad near where Bach’s body was discovered in
weeds on Sept. 17, 2011.
LaSalle said the FBI determined the stain was blood, although “very faint,”
and analysis showed a DNA match for Bach but no match was determined for
The only items where a DNA match was made for McCowan was from swabs taken
on the keyboard and back of his cell phone and also a shirt that he was
wearing when booked into the Porter County Jail, LaSalle said. Bach’s DNA
was not found on it, she said.
Swabs taken from places on Bach’s body and her fingernails on both right and
left hands yielded no DNA profile for McCowan.
The swab that was taken from underneath Bach’s left breast contained four
out of 18 DNA strands that were not hers and could have come from another or
more persons. When asked about the FBI report mentioning that the DNA came
from an “unknown female,” LaSalle said it is possible they could have come
from a male.
The FBI determined the DNA came from that of an X-chromosome which both
males and females possess, LaSalle said. There was no trace of DNA from a
Y-chromosome, that is exclusive to males, from the swab, LaSalle said. She
testified that she “couldn’t say with 100 percent certainty that it is
female DNA” because “such a small amount of cells” were found.
LaSalle said that no DNA match came back from the stains on the black and
gray sweatshirt Bach was wearing at the time of her death, not from McCowan
or even from Bach.
Frost inquired as to why Bach’s DNA would not show up on her shirt to which
LaSalle replied it could have been washed off by rain or be affected by
weather in some way. DNA could also be cleaned off of clothing if it is run
through a clothes washer or by other chemicals, she said.
She also said there are people who “sluff” or shed DNA constantly and then
there are others who don’t “sluff” at all.
“There are many different factors to getting DNA off an item,” LaSalle said.
“Do you know if Dustin McCowan is a ‘sluffer’?” Barnes asked.
“No, I do not know that,” LaSalle answered.
The FBI also reported that not enough of Bach’s DNA, or anyone else’s, was
found on swabs taken from her steering wheel and her emergency light button
inside her car to make a profile.
LaSalle said that no DNA evidence doesn’t rule out that a person came into
contact with those items. “I was just not able to generate any DNA types,”
A juror’s written question asked LaSalle if it was possible the DNA found on
Bach’s left breast could have come from someone who she shared clothing
with. “Yes, it could be from anyone. It’s just a small amount of cells.”
Earlier on, Brett Mills, a firearm and tool mark examiner with the FBI, took
the stand and testified the bullet extracted from Bach and the bullets in
the Federal .38 special Hydra-shok cartridges taken into custody from Dustin
McCowan’s father, Elliot McCowan, shared similar design characteristics but
he could not say if the bullet that killed Bach was from the same type
The Federal .38 special cartridges and bullets are a type that is very
popular with major gun manufacturers, he said.
Defense attorney John Vouga, in cross-examination, probed if Mills could
give figures as to how many of these types of bullets are purchased in this
area. Mills said bullet sale statistics are not his expertise and said Vouga
would have to pose that question to an agent of the Bureau of Alcohol,
Tobacco, Firearms and Explosives.
During the cross-examination, Mills said the bullet could have been fired by
multiple types of guns.
Meanwhile, Mills, in direct examination, testified that in his own opinion a
knife with a “single-bladed edge” was stabbed into the tire of Bach’s gold
Pontiac G6 and that the Phillips head screw embedded in the tire was likely
run over as it showed no indication of tool markings.
The “lightning-bolt shaped” cut made to the left sidewall of the tire was
likely made when the knife penetrated through the rubber and the rubber
resisted causing friction when it ripped, Mills said.
Vouga asked Mills if he knew any knives that had a lightning bolt-shaped
blade. “I do not,” Mills replied.
Mills said it is a possibility that the screw caused the tire to flatten
down to its base and the slice could have been made by the wheel rim.