As an employer, it is your responsibility to ensure that you are hiring the right candidate for the job. To do this, you need to verify the references of potential candidates. This process can give you an insight into the candidate's skills and strengths, as well as their job performance in previous positions. When verifying references, it is important to remember that the people on a job candidate's referral list are the people they want you to contact.
However, if you know someone else who can provide more information about the candidate, don't hesitate to contact them. It is often easier to trust someone you know than to trust the word of someone you've never met. For a hiring manager, a solid reference interview can also give you an enormous advantage in managing a new employee. You never know when you might need to check your grades when evaluating the candidate for a potential hire, so don't miss this important step.