They are words that Elizabeth Noble now has tattooed on her wrist, but the thought of her son's final moments, before he died in a deliberately lit fire, continue to haunt her.

"What was he doing for the previous five minutes? How long was he alive after he sent the message?" Mrs Noble asked during a sentencing hearing for her son's killer on Friday.

"How long do I continue on knowing that he was alone, knowing that he was going to die in a room by himself. Why didn't I have my mobile in the bedroom with me? I could have at least rung and talked to him."

Convenience store owner Adeel Ahmad Khan, 46, has been found guilty of the murder of Mr Noble, 27, and the manslaughter of Bianka O'Brien and her baby son Jude, after he set fire to his Rozelle shop, triggering a catastrophic explosion, in September 2014.

Mr Noble lived directly above the convenience store, which Khan had rigged with an elaborate network of petrol containers as part of an insurance fraud scheme, while the O'Brien family lived above a phone shop next door.

Khan was also found guilty of one count of causing grievous bodily harm to Mr Noble's flatmate, Todd Fisher, one count of wounding a second flatmate, Corey Cameron, and destroying the building for financial gain.

While his flatmates managed to jump over the balcony of the collapsing building, Mr Noble's bedroom door jammed and his window had metal bars.

In his harrowing victim impact statement, Mr Cameron said he had remained on the balcony, calling back to Mr Noble, until he could no longer hear a response.

"After escaping what I thought would surely be the end of me, I had to helplessly listen to my best mate, Chris Noble, scream for his life," Mr Cameron said.

"The guilt, fear, anger, I felt at this moment still distresses me to this day, I can still hear the haunting echo of his cry."

Mr Noble's younger sister, older brother, grandmother and father also prepared statements for the NSW Supreme Court hearing.

Mr Noble, who was described as affectionate, generous and athletic, had returned from a trip to South America only eight days before he was killed.

His father, Ross, said whenever he passed a property with bars on its windows he now wanted to tell the owners to remove them. He also described the last time he got to hug and kiss his son.

"That was the day we went to the Glebe mortuary and were able to hold Chris who was wrapped in a white sheet because he was so badly burnt … no one should ever have to do that," he said.

"Even after nearly two years I cannot eradicate from my mind those last few moments of Chris being trapped in his room. Those circumstances are with me continually."

Mrs O'Brien father Bill Keremelevski said his family had suffered an "unimaginable tragedy" due to one man's selfish actions.

"Bianka was not just a daughter, a granddaughter, sister or cousin, she was the shining star in our family. My friend," he said.

"Mr Khan, what you have done - you can't even imagine how many people you have affected and how many hearts you have ripped out."

Khan, a father of three, categorically denied he was responsible for the explosion and fire, saying he was robbed and tied up by three armed men for up to five hours.

The hearing heard that he had not offered an apology nor shown remorse since he was found guilty by a jury last month.

He had been in protective custody in prison, and had twice been assaulted following publicity about the case.

Khan is due to be sentenced next Friday.