Austin Sigg judge OKs use of defense brain expert

GOLDEN, Colo. - The judge in the case of a teenager charged with killing 10-year-old Jessica Ridgeway has ruled that the defense can introduce expert testimony about adolescent brain development.

But Judge Stephen Munsinger warned Wednesday that the expert can speak generally on the topic -- and not specifically about the mental state of Austin Sigg.

Sigg has pleaded not guilty to kidnapping, killing and dismembering Ridgeway last year.  She was abducted as she walked to school last October in Westminster.  He's also charged with attacking a female jogger at a nearby lake in Westminster.

The Denver Post reported (http://ch7ne.ws/18OuBH7) that prosecutors expressed concern the defense is setting up a mental state defense. Munsinger told Sigg's attorneys that they will have to justify the testimony's relevancy to the case.

During a 911 call played during a court hearing, a person identifying themself as Austin Sigg admitted to the crimes.

"I murdered Jessica Ridgeway -- I have proof that I did," Sigg is heard saying on the recording. "I'm giving myself up completely, there will be no resistance whatsoever."

When the dispatcher asked Sigg if he had a criminal history, he confessed to the second crime.

"The only other (incident) was Ketner Lake, where a woman was attacked. That was me," Sigg said.

Sigg's trial is set to begin Sept. 20.   He faces the possibility of life in prison, if convicted.