This story is an an example of how the label "honor crime" is used to justify murders of all kind. The murderer knows that to put the word "honor" before his crime is to get a reduced sentence and lots of sympathy. In this case, the man didn't kill his sister or wife for "honor" as usually is the case. He killed his father, his second wife, and their son. The first news mentioned an inheritance dispute to be behind the killing, which makes sense. But now the killer is saying that he was motivated by honor, that his father was a drug addict who would not reform. So he killed him. And his wife. And his five-year-old son. Oh, but he said that killing the boy was mistake. He just failed to see him lying there next to his mother.
It's interesting that he doesn't have any explanation why he killed his step mother.