A scene from “Unfinished Business”

Ben Gibbons: [after Jessica exposes him as the murderer] I didn't start out to kill him. I really didn't. I just wanted him to know how much hurt he had caused. Everybody had got off the bus except Stoner and the young guy. I was working around the engine, just stalling, waiting for Stoner to be alone. He was mean, cold-mean. He said he didn't give a damn about some dumb kid that just happened to get in the way. He had done his time, and there was nothing anybody could do. "Dumb kid." The sweetest little girl you ever saw in your life. Well, all of a sudden, I just went crazy. I couldn't think about anything but killing him. When I got off the bus, I was shaking so hard, I thought I was going to pass out. I realized what I'd done. I had killed a man. I was no better than he had been. Just then, I saw the captain come out of the diner and get on the bus. I thought I was a goner. But when I looked in the window, the captain was going through Stoner's pockets. Then he grabbed the suitcase and took off. I just stood there for a few minutes. Trying to figure out what to do. That's when I knew I had to stab him in the neck with the screwdriver.

Sheriff Amos Tupper: But why?

Ben Gibbons: Guess you know the answer to that.

Jessica Fletcher: You knew the coroner would figure out that Stoner died of strangulation and not a stab wound. By confessing to killing Stoner with a screwdriver, no one would figure you were the original killer. As Mr. Downing said a few moments ago, the police would check backgrounds, prior relationships. Downing thought he'd be a key, perhaps the only suspect. You thought the only way to escape arrest for Mr. Stoner's murder was to confess it.