Denis O'Brien (police officer)

Denis O'Brien is a common name, and without further specifying details such as rank, department, or any notable achievements or incidents involving a police officer of this name, it is impossible to create a comprehensive encyclopedia entry. To create a useful entry, more information is required. This could include:

• Jurisdiction: Which police department or force did/does Denis O'Brien serve? (e.g., NYPD, Metropolitan Police Service, etc.)
• Years of Service: What are the dates of his service?
• Rank: What was his highest attained rank?
• Notable Cases or Actions: Were there any significant events or cases involving Officer O'Brien that contributed to public knowledge or recognition?
• Awards or Recognition: Did he receive any medals, commendations, or awards during his career?
• Retirement or Separation from Service: Under what circumstances did he leave the force?

Without this additional contextual information, this entry remains incomplete. Specific details are necessary to distinguish this individual from other people with the same name.