Anybody who willingly sets a family pet on fire is an effing psycho. It's totally obvious this guy is a redneck, psycho, piece of shit. The exact type of person you'd expect to rape/murder someone...
Did the police plant evidence? Probably. Does that change the fact that Avery is better off in jail? Nope.
Let the a-hole rot. He clearly has a track record of effed up actions, only a matter of time before something happens again.
You may be right,he may need to rot in jail. But at the same time you can't have Police departments planting evidence all over the place just to get a conviction. You are probably a NICE Person. How would you feel if the Police planted evidence on you?? The Police need to be in jail too.