The protection of the banks is naturally the most important work that such an agency can perform.
The National Bankers' Association has eleven thousand members.
"Pinkerton's Bank and Bankers' Protection" also has a large organization of subscribers.

These devote themselves to identifying and running down all criminals whose activities are dangerous to them.

Here the agency and the police work hand in hand, exchanging photographs of crooks and suspects and keeping closely informed as to each other's doings.

Yet there is no official connection between any detective agency and the police of any city.

It is an almost universal rule that a private detective shall not make an arrest.