She was prompted to speak out after concerns were voiced that Sous, who came to New Zealand as a refugee when he was a boy, had language difficulties.
"There was not a language problem," she said.
Having attended court hearings and a family conference, she said she recalled asking the boy about his favourite subject at school.
"English," he replied.
Harris said: "He spoke well, so not a hard-done-by person by any means."
Last week's fatal shooting prompted Harris to email her children, saying: "I can tell you it was well-earned."
She told her children: "Do not let pity or dread overcome you, I was in the courtroom and at a conference with him. I have my thoughts and they are not good."
She told them Sous had broken into her elderly mother's home three times in two weeks - including breaking a window and entering the house as she slept.
She said her mother was not Sous' only elderly victim; a 93-year-old man had earlier been burgled by Sous and other teenagers.
"His dad now says he got in with a bad crowd. He was the bad crowd. After those first robberies he broke into his parents' house and stole his mother's wedding ring."
She said his father's reference to Sous being a "good boy" was better stated: "He was our son, we loved him."
"He was a bad boy or why was his wife beaten up enough to ring for police and why did this so-called 'good boy' have - and present - a sawn-off shotgun at the police?
"I am not sorry that he has gone he had so many chances and he chose the worst way.
"Sorry for his parents who were always hopeful that he might be better."