Oates left Ann Arbor and became the police chief in Aurora, Colorado, in 2005 after the former chief, Ricky Bennett, was demoted for his department's failure to stop Brent J. Brents from committing sex crimes. Oates began his career in Aurora by building up a relationship between the police department and minority communities, specifically focusing on the black community whose members felt that the police force was used against minorities. During his first five years in Aurora, he oversaw a 30% decrease in the crime rate.