As three teenagers were driving home from the gym one afternoon last June, a group of men standing on a street corner in Panania allegedly started yelling abuse at them.
Rather than keep driving, Joshua Dillon, 18, James Rivera and a 17-year-old stopped, allegedly got out of their white Hilux ute and, within seconds, a fight erupted between the two groups.
Dillon, Rivera and the 17-year-old were subsequently charged and refused bail.
Now, police fear repercussions from the deadly brawl may have reared their head in the most chilling way on Good Friday when Joshua's younger brother, 15-year-old Brayden, was shot dead in his bed.
Brayden, his mother, his step-father and his step-siblings, aged 1 and 7, were all asleep in their Glenfield home, in south-west Sydney, when a gunman kicked down the front door just after 6am.
It's believed Brayden's mother confronted the masked man but he yelled threats and pulled out a pistol, forcing her to flee to a bedroom.
He then walked to Brayden's upstairs bedroom and shot him twice in the head at point-blank range as the teenager lay in bed, Detective Chief Inspector Mark Brett said.
A key line of inquiry is whether the "execution-style" shooting was a revenge attack for the alleged murder by Joshua Dillon, police sources said.
However, Brayden was also well-known to authorities for his own involvement in local gang activity and violence.???
Fairfax Media understands authorities had been called to the family's rented home in Moresby Avenue at least three times in the past two years for incidents involving Brayden.
???In one incident, he allegedly tried to attack his mother with a knife.
In another, he was allegedly smashing windows and property in the home, forcing his pregnant mother to call paramedics out of fear.
???Friday's shooting prompted a war of words to erupt on social media between teens claiming to belong to rival groups in the Campbelltown area.
"It's called revenge. He deserved everything his just got [sic]," said one teen, who claimed the shooting had been planned for six months and that she warned Brayden two weeks ago that his "head was wanted".
Posted another: "two people are dead and two are in jail and if this keeps going on people are gonna start dying... someone was gonna retaliate because of adam's death but who's to say people aren't gonna stop retaliating and sooner or later there's gonna be a bigger issue."
???It's understood the two groups who brawled on the Panania street corner in June 2016 were rivals divided along geographical and ethnic lines.
One boy familiar with the ongoing conflict said Abu-Mahmoud belonged to a group of Bankstown boys who often clashed with a group of boys from the East Hills/Panania area that included Joshua Dillon.
Abu-Mahmoud was allegedly stabbed four times and died on the roundabout with a knife, allegedly belonging to Rivera, lodged in his back.
It appears tensions have simmered in the area ever since the stabbing. Still, friends of Brayden appeared shocked that he may have been drawn into it.
"Taking this precious boy from us for no reason... he didn't deserve nothing [sic]," posted a woman claiming to be his sister.
Another friend posted: "Brayden was a lovely boy and he didn't deserve anything he got. No one deserves to be shot in the head."
Police said Brayden's family were not able to identify the gunman or see his face properly.
On Friday, investigators were hunting for a man described as being aged between 18 and 20, of thin build, and wearing grey tracksuit pants, a navy hooded jacket and white runners.
Police said that anyone who sees this man should not approach him and should call triple zero immediately.???
