Whenever the City Clerk receives an application for a license as an intelligence officer, private detective or private investigator he shall refer the same to the Department of Safety for investigation. The applicant shall subject himself to interrogation by the police, permit himself to be fingerprinted and register with the police any guns or other weapons which he proposes to carry on his person. If the Police Department finds the applicant trustworthy and acting in good faith, the Chief of Police shall so report to the Director of Safety who shall approve the application and authorize the City Clerk to issue the license on payment of the proper fee.