GOLDEN, Colo. (AP) — Defense lawyers on Friday questioned how DNA evidence was handled in the case of a teenager charged in the slaying and dismemberment of a 10-year-old girl in suburban Denver.

Austin Sigg, 18, has pleaded not guilty in the October death of Jessica Ridgeway of Westminster. He also has denied charges stemming from an attack on a 22-year-old jogger at a lake in the girl’s neighborhood five months earlier.

Kathleen Fetherston, director of the state crime laboratory in Denver, testified in court Friday about possible DNA contamination in both cases.

She said DNA from the jogger attack was tested in a batch with DNA from other cases, and irregularities were found in the tray holding the samples. She added that no contamination was found in the case involving the jogger, and that Sigg’s DNA was tied to that sample.

DNA evidence in the Ridgeway case was tested alone in one tray, and two memos were generated about possible contamination in those samples. Fetherston did not provide any details about how that contamination might have occurred.

Defense attorney Mitch Ahnstedt said such revelations call into question the reliability of the lab work performed by the Colorado Bureau of Investigation, which tested the samples in both cases.

After the hearing, CBI spokeswoman Susan Medina said if irregularities are found in a DNA sample, scientists “identify where it happened, backtrack and retest.”

“There are all sorts of checks and balances. … We feel it’s critical to be proactive as well as transparent,” said Medina, who declined to comment specifically about the Ridgeway case.

The judge didn’t rule on the quality of the DNA evidence but did order CBI to try to recover internal correspondence about the testing and give it to the defense.

Sigg is charged with murder, kidnapping, sexual assault and robbery, as well as three counts of sexual exploitation of a child after authorities said they found child pornography during the investigation. Investigators say Sigg has denied sexually assaulting Jessica but confessed to killing her.

The fifth-grader disappeared while walking to school Oct. 5. Hundreds of police and residents searched for her, and parents escorted their children to and from school. Her torso was found in a secluded park Oct. 10.

Sigg, who is scheduled to go to trial in September, can’t face the death penalty because he was 17 at the time of the slaying.

By Thomas Peipert, AP Writer (© Copyright 2013 The Associated Press. All Rights Reserved. This material may not be published, broadcast, rewritten or redistributed.)


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