There's a child rapist that lives next to the elementary school my little sister goes to?

I'm 16 .I looked on watchdog,com and found that there is a person convicted in 1979 for raping a 13 year old girl. he lives 0.43 miles away from the school -- about 4 blocks. My sister goes there. He's 73 years old btw. I want to make sure he doesnt hurt anyone else. i was thinking of throwing rocks through his windows, posting flyers stating that he's a sex offender around the area, vandalizing his house with the word "pedo" spray painted on the front of his house and "rapist" on his front door. my friend (17) did this before for fun (which is wrong) so he'd help me out but I want to do it alone. i'm serious about this. hearing about rape and child abuse makes my stomach turn and my fists clinch. i've examined his house from my bike and his face from far away with binoculars, i know that's where he lives and i compared his face to the one of the sex offender registry website and it matched completely. what should i do about this. i don't think telling the school principal would help because she wouldn't do anything (i know her) and if i did something after i told her she'd know it was me and get me in trouble. so telling an adult is out of the question. sometimes when the government fails at properly enforcing laws and punishing those who break it, you gotta take the law into your own hands and im ready to face the risks because i dont want my sister to be harmed