In July, a confrontation occurred between William Costello and a man collecting petition signatures. Costello was arrested and charged assault on an at-risk adult.
His DNA was taken following the arrest and subsequently linked to three unsolved sexual assault cases from 2008, 2010, and 2011.
Costello's charges allege he sexually assaulted a 13-year-old girl in March 2008, a 22-year-old woman in August 2010 and a 49-year-old woman in September 2011.
In two of the attacks, Costello allegedly claimed he was a police officer.
He was formally charged with two counts of second-degree kidnapping, two counts of sexual assault on a child, three counts of sexual assault and two counts of impersonating a peace officer.
Costello was taken to the Denver Detention Center and is being held on a $200,000 bond.
His first court appearance is scheduled for Tuesday.
Under Colorado's Katie's Law, DNA samples are collected from suspected felons when they're arrested. Previously only people who were convicted of a crime had to submit a sample.
(KUSA-TV © 2012 Multimedia Holdings Corporation)