I thought about how I would frame you and how I would kill my sister. I finally figured out how I was going to kill her, I would poison her with Ethylene Glycol, but how would I frame you? Then I got it. So I then needed to decide when and how I was going to execute this plan. I would get your finger prints somehow, then take some of your DNA and leave it at the crime scene, report my sister missing and say the last time I saw her was before she went over to your house and then boom your framed. First I need to find a motive for you killing her so it would be more believable. Then I remembered something that happened last week. She had cheated on you with Evan, the quarterback. I saw them making out in the under the bleachers. I figured that would be a great motive. Now all that's left to do, is execute the plan.