Here is my theory on how I think Chanel #5 is the killer. Okay, so this is going to be going off the theory that there is copycat killers. At the beginning of the series, I believe Chanel DID injure Melanie(Girl that got sprayed with acid) and killed the old kappa sister that lived away from everyone else. I'm going to start at the part where Red Devil kills Chanel #2. I think that when Chanel was getting ready to kill one of the pledges with the lawnmowers she saw through the window Grace, then texted Chanel #5 to come down and stop Grace before seeing she saw the red gloves(belonging to the red devil costume of Chanel) which we saw but Grace didn't notice. Also if you're wondering why you saw the red devil in the window how could the gloves be there, she hadn't finished dressing yet. Next, the kappa sister(mandy) is killed but you wonder, how would the red devil know she talked to them unless...Chanel #1 has cameras all over the house watching. Now I doubt that she would look at them, then get Mandy because she has no relationo or she didn't want secrets told. But what is more like is the Red Devil is watching the tapes and that's how he knew about the Japanese made up stories and the 1950's car killer because he was watching the cameras. What is not explained is why the killer would be in the back of Chanel #5's car but if her brother Boone was pranking her and it freaked her out so she got revenge killing him. There's a lot of loopholes but tell me what you P.S. Ms. Bean was killed because "she knows everything that goes on in this house so CHANEL KILLED HER ON PURPOSE so she could get away with her one murder because she said she'd do ANYTHING TO SCARE OFF THE PLEDGES. EVEN MURDER? But I think she grew past that phase and doesn't kill anymore because she grew to like her sisters.