Years ago, a very, very nice woman took a chance on me when I was unemployed, and hired me to work in her business. I liked her, and she was a very reasonable employer. I was happy with my working conditions, salary, and benefits, and because she was willing to employ me when no one else would, I felt an enormous amount of obligation to her, and so I worked very hard in several of her retail locations, until I was finally offered the chance to manage one of her stores.
Unfortunately, that was my downfall. The previous manager at that location was one of the owner's friends. When I took over, I did what any responsible manager would do: I inventoried everything, and found discrepancies of hundreds of dollars. I immediately reported the discrepancy to the owner, and was reprimanded. She had two possible reasons to offer for the discrepancy, either I was taking the opportunity of the new position to arrange a massive one-time theft, or I was accusing the former manager of stealing, because she had been promoted.
Neither of these were true. I simply reported a discrepancy and asked what I should do. But from then on, my reputation in the company was tainted. I'd already had one run-in in a previous location, because another employee on the same shift asked me to complete a sale he had started to ring up on his register, and I offered to restart the sale on my register, but the customer refused, and the other employee left his register to use the bathroom, and the customer did not want to wait. That evening, his register was short (mine had always been exactly on). The owner took half the shortage out of my check, and half out of the other employee's check, because I had touched the register.
But back to the new location: I spent hundreds of hours cleaning, both in the retail area and the stock area. I kept meticulous records of everything, spent weeks cleaning out expired stock, and developing relationships with vendors. But there was one thing I could not do; I could not keep one other employee from using my register. And then, consistently, my register came up short. However, it came up short only when I shared the shift with that particular employee. So I meekly accepted the deductions from my paycheck, and asked the owner what I should do to keep this employee from using my register. She then told me that he was a long-time employee and would never think of stealing from her. (Well, I didn't think of it either, but that's another story.) I had to shrug and say, "Well, anyone can make a mistake." I realized at that moment that the situation would never get any better, stuck it out for another month, and then gave my notice.
I don't bear the owner any ill-will, but it was clear to me that she was allowing her friendship with these two employees to affect her business. And there's a powerful lesson to be learned from this experience; you cannot let a blind spot interfere with your business operations. It is possible for your friends to do a bad job. It's possible for your friends to make mistakes. It's possible that an employee you suspect is actually scrupulously honest. And it's possible that your preconceived notions about your business are damaging your bottom line.
So when you are dealing with some situation in your business, it's important to keep an unbiased viewpoint. If you are not able to do this yourself, then you need to hire a third party to investigate. Whether that third party is a forensic accountant, or someone to review security videos, or someone else, you'll be doing yourself, your business, and all your employees, including your friends, a favor.