Begin with an interesting fact or description about the person you interviewed. This immediately gives a context for the interview and grabs the reader's attention. For example, you could start with, "John Smith has the face of a saint, with eyes that are gentle and appealing."
Explain why you chose the interviewee by transitioning into a sentence that explains to the reader why she should care about your subject. For example, from the description given in Step 1, you could continue with, "And yet, behind those kindly eyes are the memories of a killer sentenced to death 20 years ago, but still alive because the law allows him to file for multiple stays of execution."
Conclude your introduction with a strong thesis statement that establishes the purpose of your interview essay. Your thesis statement should tell a reader what to expect in the body of your essay. For example, if your interview was about the ineffectiveness of the death penalty, your thesis statement could be, "The death penalty cannot be an effective deterrent if inmates on Death Row are never executed because of endless opportunities to delay justice."