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 Sheriff’s Police.

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 McCowan’s DNA.

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,” she said.

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 cartridge.

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.