Bradley Craig Mottram jailed 13 years for killing his mum, Simone

A NSW man who stabbed his mother to death as a teenager has been sentenced to at least 13-and-a-half years in jail.

Bradley Craig Mottram, 22, hit Simone Mottram, 51, over the head with a bottle of bourbon and stabbed her in the chest, neck, upper abdomen and face after she said something that made him snap at an Inverell home, in northern NSW, in October 2015.

The NSW Supreme Court on Thursday heard Mottram had a dysfunctional upbringing and struggled in the lead-up to the killing with substance abuse and deteriorating mental health.

"A dreadful crime has been committed by a very troubled young man," Acting Justice Peter Hidden said in sentencing.

Simone Mottram was killed in October 2015. She is pictured inset with her son, Bradley.

Simone Mottram was killed in October 2015. She is pictured inset with her son, Bradley.

On October 19, 2015, Mottram was at the Inverell property alone with his mother when he launched the attack, first punching her and bashing her with the bottle.

He then went to the kitchen and grabbed a carving knife before repeatedly stabbing Ms Mottram to death.

The court heard Mottram placed the knife on Ms Mottram's body and covered her before fleeing the scene in her car.

Following his arrest, he made admissions to the crime and said: "I didn't meant to do it, she just wouldn't shut up".

Police found notes written by Mottram before he was taken into custody which he titled "My Last Words" in which he repeatedly insisted the attack wasn't planned.

"I was drunk. It was an accident. She just, she wired me from birth. I'm sorry. I didn't mean to," he wrote.

"Oh Jesus, what have I done?"

Mottram later told relatives he remembered about five per cent of the incident because he was coming down off drugs, but he was pleased he didn't remember it.

Justice Hidden sentenced Mottram to 18 years in prison with a non-parole period of 13-and-a-half years, saying it was clear the offence took place against the backdrop of mental health issues.

"I think it is unlikely he would offend again in this way or at all," Justice Hidden said.

Mottram will be eligible for parole in April 2029.

Australian Associated Press