First off, you have to make sure it is the same person and you will need a date of birth or social security number to do that. Second, a blanket search over the internet isn't going to give you a thorough story of what the circumstances was and third, most people do thorough backgrounds checks and will not hire someone with a violent crime record.
There is a really good chance that the interviewer is not your guy unless he is the owner and even that is iffy. I used to work at a prison and we had this kid there. He went down for 7 years for involuntary manslaughter. Now on the surface that sounds really bad. But the reality is is he took his date and some friends to prom. Afterwards they did a bit of drinking and he was the driver. (The kid was only 16 at that time). Needless to say they got into a car accident that killed his girlfriend that bumped his charge from DUI to involuntary manslaughter. The moral of this story (true btw ) is that you really don't have enough information. What if it is him and he shot an intruder trying to rape his wife? What is he is an old man being attacked by some teenager and pulled out his gun and self defence, but still the judge felt he needed to some time? (I've seen that one to).
If your spidey senses didn't go off during the interview, but did go off afterwards, then it's most likely fear. I would suggest getting more information on this person, if you haven't already and then make a judgement call.
Maybe your empathy button was on and he's not dangerous to you.
He killed somebody - but what kind of murder was it? Cold-blooded, premeditated? Rape plus murder?A stranger, or hiswife's lover? Self-defense? A bar fight? Is he a serial killer or was this just one time he lost his temper and went too far?
I think you're right not to take the job if it would make you nervous to work for him. But I worked with a guy who killed somebody. He didn't do any prison time because the guy was trying to break into his house and attack him and his girlfriend. He was a nice guy and I wasn't afraid of him. But you have to follow your gut.