There was a crew of pirates, but they’ve been having some trouble on their ship

Every week a crew member turns up dead with their throat slit, so they know it’s somebody on the ship killing them. For convenience, the crew all go by initials of one letter, all that remained was EE, II, and AA. The captain called each member in one by one starting with EE. He says “EE, what do you know about these killings? was it you?” He replies “No captain it wasn’t me, the only people I kill are your enemies.” He says “you better be telling the truth” and sends him out of the room. He calls in II. “II, what do you know about the killings? was it you?” He replies “Captain, I saw EE looking suspicious the other day, I think it’s him. I would never kill one of our crew members” He says “you better be telling the truth” and send him out of the room. Lastly, he calls in AA. He says “AA, i’ve known you a long time and you’re my right hand man, I trust that it’s not you killing these people so I need you to tell me everything you know” He replies “II cappin”