Steve Ainsworth spent over three decades with the Boulder County Sheriff's Office Investigations Section, establishing himself as a leading authority on homicide investigation and death scene examination across the American West.

During his tenure, Ainsworth investigated more than 2,500 deaths of all causes and manners—a career marked by meticulous casework and an unwavering commitment to solving the unsolved. For the final 16 years of his time with the Sheriff's Office, he focused exclusively on major crimes against persons, with particular emphasis on homicides, cold cases, and fugitive investigations.

Beyond investigative work, Ainsworth became a sought-after instructor and mentor. He taught crime scene investigation at the Colorado Coroners Association Conferences, Wyoming Coroners Association, and Indiana State Coroners Association. Within his own agency and across Colorado's law enforcement training infrastructure, he led in-service programs on investigating death, robbery, and assault cases—the Sheriffs Training Institute and LEEPAC group among his training partners.