If you are facing a crime, the police is the appropriate authority to start an investigation. However, the police sometimes have a lack of time or insufficient capacity. In that case it can be very useful to contract a security organization, specialized in criminal investigation work, among other things.
Because the government cannot investigate everything, a private detective agency has a broader field of activity than the police. Capital Investigations is a private detective agency and is presented as a private detective (for individuals) or a company detective (for companies).