Your head bookkeeper may have real talents in this direction--if he is not above using them.

Naturally, the first essential is brains--and if you can give the time to the matter, your own head will probably be the best one for your purposes.

If, then, you are willing to undertake the job yourself, all you need is some person or persons to carry out your instructions, and such are by no means difficult to find.

I have had many a case run down by my own office force--clerks, lawyers, and stenographers, all taking a turn at it.

Why not?
Is the professional sleuth working on a fixed salary for a regular agency and doing a dozen different jobs each month as likely to bring to bear upon your own private problem as much intelligence as you yourself?
There is no mystery about such work, except what the detective himself sees fit to enshroud it with.