The investigation prompted one of th largest criminal searches in Colorado history, with more than 1,000 law enforcers from 40 agencies deploying everything from high-tech forensic science to neighborhood canvassing.
Yet it was a phone call from Mindy Sigg that led police to arrest her 17-year-old son, Austin. That call came a day after authorities announced a definitive link between Jessica's death and the May 28 attempted abduction of a jogger - information police had known for more than a week, a source close to the investigation told The Denver Post.
Authorities, citing a judge's gag order, will not discuss the case with the media, and they have not disclosed what exactly led the mother to call Westminster police about her son.
Veteran investigators say police often release information strategically to flush out killers.
Read more of the story by Jeremy P. Meyer, Sadie Gurman and Jessica Fender in the Denver Post.
(Copyright 2012 The Denver Post)