Jessica Ridgeway's suspected killer challenges FBI profile

KANSAS CITY, Mo. - FBI agents use profiles to detect and classify the personalities of people based on the crimes they commit, but sometimes the suspects elude those profiles.

In the Jessica Ridgeway investigation, 17-year-old Austin Sigg, arrested on suspicion of Ridgeway's murder, did not match the original FBI profile released to the public.

"It's not exact science and you can't take it too literal," said Michael Tabman, a former FBI agent. "You have to use it as a guideline. Sometimes it's right and sometimes, like in this case, it's way off."

According to Tabman, FBI profiles are derived from historic data compiled about convicted criminals. In the Jessica Ridgeway investigation, FBI profilers initially said the suspect may leave town or alter his appearance -- comments that baffled Tabman.

"We don't see, too often, them changing their appearance or leaving town in these particular cases," he said. "So, I was a little surprised by that."

Sigg lived only a mile from Ridgeway, and his appearance on the day of his arrest was still very familiar to those who knew him.

With sealed affidavits, authorities are releasing few details about the investigation. On Oct. 10, five days after her disappearance, Ridgeway's body was found dismembered in a park not far from her home.

According to a CNN report, some of Ridgeways body parts were found under Sigg's home.

Prosecutors plan to charge Sigg as an adult by his second court appearance, scheduled for Tuesday. Prosecutors said, though, that even if he is tried as an adult and convicted of first-degree murder, he cannot face the death penalty or mandatory life in prison without the possibility of parole because he is still a juvenile.