Means, if having an affair with Mrs. Shears, at some point he could have received the key to her shed, having access to the tools.
There are a few things that made me suspect that Mr. Boone killed Wellington. He doesn't like Chris mentioning Mr. Shears, for maybe whenever "Shears" is mentioned, he's reminded of his crime. It's a possibility for an inexperienced killer to crack when they hear the name of their victim. Also when Christopher saw his father crying and drinking, Chris asked if he was sad about Wellington, and he replied "Yes Christopher, you could say that. You could very well say that." But in the car ride back he said that the dog wasn't important and he didn't care about the dog.
Now, in every mystery, there's always a red herring, which acts as a fake clue, a clue that has nothing to do with the actual mystery. Like when Mr. Boone said that "Mr. Shears is evil" I started thinking that Mr. Shears might have something to do with the murder, what if he moved out because of the affair between Mr. Boone and Mrs. Shears. Maybe he was angry at Mrs. Shears. BUT. Why would you kill the dog two whole years later? It just doesn't add up because most crimes are consistent events.
Now for me to prove that Mr. Boone DID KILL Wellington. He is so protective of the subject. After picking Chris up from the police station, Chris starts asking questions about Wellington. What does Mr. Boone do? He flips out. He tells Chris that the "dog isn't important" but if it isn't important, why be so protective of the subject? He constantly tells him to "leave it" And sure maybe he's just trying to keep Chris out of trouble but he doesn't tell him that does he? And also, he states that "Mrs. Shears is not a friend anymore." Because he just committed homicide on her dog. Why would they not be friends anymore? An affair? Most likely...
With this evidence, I can prove that Mr. Boone killed Wellington, because of suspicious sayings, and the fact that it's totally possible that he had an affair with Mrs. Shears. Because to a guy like Mr. Boone, perfect revenge is killing the one last thing that she loved.


