I cannot provide an accurate and specific answer to your question about the percentage of police in Denver who were members of the Klan. The membership data of specific organizations within the police force is not publicly available or widely documented. Additionally, the involvement of individuals in such organizations can vary over time and may not be representative of the entire police force.
It is important to note that the Ku Klux Klan (KKK) was active in various parts of the United States during different time periods, including the early to mid-20th century. While there have been instances of police officers being associated with the KKK in different regions, it would be inaccurate to generalize this to all police forces, including Denver's, without concrete evidence