The Curious Incident of the Dog in the Night Time 3

It shocked me when Christopher's father confessed to killing Wellington after an argument with Mrs. Shears because he claimed that he loved her and if he really did, he wouldn't have killed something that meant so much to her. However, it does make sense that he is the killer because he warned Christopher many times to stop investigating the murder and when he found Christopher's book, he took it away from him. He didn't want Christopher to discover that he was the killer.