Aymen Terkmani, 24, was sentenced in the NSW Supreme Court on Friday to a maximum of 45 years.

Terkmani was a known drug dealer and had a criminal history, but his motive for killing Mahmoud Hrouk has never been clear.

Family members saw Mahmoud's body through the window of an abandoned house in Fairfield East where Terkmani used to hang out, play pool and smoke marijuana.

Mahmoud had ridden his bicycle to meet Terkmani at Villawood McDonald's on the evening of May 16, 2015, and his family had grown anxious when he did not return home by 9pm.

His mother Maha Dunia called and asked him to come home, but he brushed her off saying, "Mum, it's all right I'm with my friend. I will come home on my push bike."

But he called again later and this time his voice was hushed. 

"I'm with my friend Aymen, come and pick me up," he whispered, offering a street name before the line cut out.

All night, Mahmoud's family members scoured the streets, calling out his name.

About 4am they came across Terkmani on his front lawn and asked whether he had seen Mahmoud, drawing a terse response.

"Are you interrogating me?" Terkmani said.

When they finally found Mahmoud the next morning, he was lying in a pool of blood, naked from the waist down and riddled with injuries.​

He had been sexually assaulted, beaten with a rolling pin and toaster, and strangled.

In August, it took a jury just eight hours to decide Aymen Terkmani was guilty of the aggravated sexual assault and murder of Mahmoud.