DNA questioned in Jessica Ridgeway case

JEFFERSON COUNTY, Colo. - DNA results are being questioned in the Jessica Ridgeway kidnapping and murder case.

In court Friday, the lead defense attorney for suspect Austin Sigg called into question the quality of work done on the DNA evidence in the Ridgeway case and the attempted abduction of a jogger at Ketner Lake.

The defense team said it has received three memos from authorities that show three DNA samples may have been contaminated -- two in the Ridgeway case, one in the Ketner Lake case.

The Colorado Bureau of Investigation report on the Ketner Lake case said the Ketner Lake sample was in a tray of other samples. CBI officials said some of the other samples were contaminated but the jogger sample wasn't.

Contamination can occur when a DNA sample is heated. Sometimes gas or liquid from one sample may contaminate another sample.

In the Ridgeway case, no details were released about the possible contamination, but officials said those samples were tested individually.

Sigg pleaded not guilty last month to 18 counts in the Ridgeway and Ketner Lake cases, despite confessing to both crimes to 911 dispatchers.

A two-and-a-half week jury trial for the case is scheduled to begin Sept. 20.

While Sigg entered a plea of not guilty, his attorneys mentioned Sigg's mental health, indicating a plea of not guilty by reason of insanity was still on the table.

If convicted, Sigg faces life in prison with the possibility of parole after 40 years. Sigg, who is 18, cannot face the death penalty because he was 17 at the time of the slaying.

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DNA questioned in Jessica Ridgeway case