Evidence was fizzling, trial told

PLATTSMOUTH, Neb. — Crucial evidence against two murder suspects had fizzled by the time Douglas County's CSI director produced DNA evidence that seemed to tie the suspects to the crime.

A DNA analyst testified Tuesday that lab tests had determined that suspects Matthew Livers and Nicholas Sampson were not the sources of DNA found at the crime scene.

Kaye Shepard of the Human DNA Lab at the University of Nebraska Medical Center testified on the second day of David Kofoed's trial on state charges of evidence tampering in connection with the investigation of the slayings of Wayne and Sharmon Stock.

Shepard testified that she gave the Douglas County CSI office the test results on May 4, 2006. Five days later, she was given three more items to test, including a piece of filter paper that Kofoed said tested positive for blood.

The filter paper contained such a strong presence of Wayne Stock's DNA that Shepard had to dilute it before running it through a machine, she said.

Shepard testified that she also took numerous precautions to ensure that no cross contaminations occurred in her lab.

During cross-examination, Shepard acknowledged that accidental contamination is possible, citing one instance in her lab in which another analyst inadvertently transferred his own DNA onto a sample being tested. That breach was identified quickly before the results were sent out.

"Even with best practices and the most extreme measures it does happen occasionally"? defense attorney Steve Lefler asked.

"Yes, it does," Shepard said.

On Monday, fellow Douglas County crime scene investigator Michelle Steele Potter described her boss as attentive and careful.

"Detail-oriented?" special prosecutor Clarence Mock asked her Monday. "Methodical? Would you agree to that characterization?"

Yes, Potter answered.

What's more, she testified, her boss knew the safeguards and proper procedures to prevent his crime lab equipment from being contaminated and later questioned for the reliability and admissibility of evidence gathered at a crime scene.

Potter testified that she, other investigators and Kofoed took necessary precautions to thwart cross-contamination at the farmhouse of rural Cass County residents Wayne and Sharmon Stock, who were murdered in April 2006.

Investigators wore disposable gloves and throw-away boots. A staging area out back stored the CSI equipment. Agency equipment was cleaned before it was packed for the 50-mile drive back to the CSI lab in northwest Omaha.

Mock argues that Kofoed planted evidence to corroborate a confession from Livers, the Stocks' nephew.

The confession later turned out to be false, and the car where Kofoed reported using the filter paper to find the blood evidence was later found to have no involvement in the slayings near Murdock, Neb.

On Monday, Mock worked to poke holes in Kofoed's assertion of accidental contamination. He argued that Kofoed adopted that position only after he was faced with another, more sinister scenario: that the CSI director had planted evidence.

Mock used Monday's prosecution testimony to raise doubts about whether Kofoed or anyone from his CSI unit even used the blood-testing kits that Kofoed claimed to have contaminated during three days of processing evidence at the farmhouse — and later used in the car.

Potter spent three days at the house conducting bloodstain analysis and swabbing stains.

"Did you see anyone using any presumptive blood-testing kit?" Mock asked her.

"Uh, no," she answered. "I don't recall it being used."

Potter said she recovered four cotton swabs of the Stocks' blood from the upstairs hallway and bedroom — and acknowledged that she failed to tape up the swab box and the paper sack where she put them.

"I did not tape them," she testified. "The swab boxes do not appear to be sealed. . . . I am pretty embarrassed by it as well."

Later, she brought the blood swabs back to the Douglas County crime lab but failed to properly secure them.

Mock theorizes that Kofoed used those swabs to plant the blood evidence onto his filter paper about a week later. Doing so would have corroborated the confession, Mock said.

On cross-examination, Potter said everyone in the CSI unit would have had access to the blood she collected — not just Kofoed.

Potter testified that the Murdock case marks the one and only time during her five-year employment in which her agency theorized that cross-contamination of filter paper equipment might have occurred.

Mock asked whether Douglas County CSI conducted any probe in 2006 to determine the source of any possible cross-contamination.

"Not that I am aware of," Potter testified.

Mock said the agency didn't adopt cross-contamination as a possible theory until after the FBI launched its misconduct investigation of Kofoed in 2008.

Retired Douglas County CSI investigator Don Veys also testified Monday that he snapped more than 500 photos from inside the farmhouse, and none of his pictures showed anybody conducting filter paper chemical tests at the scene.

But Veys, a former supervisor of Kofoed's at the Omaha Police Department in the 1990s, mostly portrayed Kofoed in a favorable light.

Veys agreed that cross-contamination is a common occurrence at crime scenes and is nearly impossible to prevent. He said accidental contamination was a likely scenario for how the blood got onto Kofoed's filter papers.

Veys said he does not consider Kofoed dirty or crooked. "Tireless, almost to a fault," Veys described Kofoed.

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