A small army of stone angels stands sentry, heads bowed, wings tucked in permanent solemnity.There is Jesus on his cross, fairy lights and candles. When the sky goes dark a small lightbox in the rockery beams "RIP JYE".

Kathy McWatters herself wears black - family and friends haven't seen her in any other colour for four and a half years now.

She still leaves a light on each night for 19-year-old Jye McWatters, the grandson she reared like her son. Jye was a Lake Illawarra High graduate; a lover of urban-inspired caps and bright white sneakers, pretty girls and BMX bikes. A prankster. Her "clown in a crowd".

The angels surround the spot where the teen's lifeless body was discovered on Boxing Day 2015, partially beneath a trailer, with two garbage bins pushed in front of him, a fatal gunshot wound to the back of his head.

With so much time now passed, and still no killer found, Mrs McWatters has only her lawn memorial for comfort. "I stand there and I stand, and I stand, and I stand. Then I take all the blame onto myself because I never woke up that night. I think, 'why didn't I wake up that night?'."

Jye went to the grave with his killer's identity a secret.

He had been at a house party in a nearby street that Christmas evening, but came safely home. He told his nan and his little brother Jaydan that he loved them before he went to bed, only to be found inexplicably outside the house the next morning.

A breakthrough in the murder mystery seemed imminent in August 2016, when police charged a man with concealing information that may have delivered them their killer.

But the charge was dropped, the pool of suspects widened.

Police have in the past indicated Jye was feuding with multiple parties when he was killed, but say these fights were "typically [the result of] testosterone levels - to do with the way young men of today see themselves, and the way that they use force as opposed to talking any problems out," rather than matters - outwardly at least - of life or death.

Police brought a clairvoyant to the McWatters house to assist with their investigation, about two years ago.

Mrs McWatters watched the woman hold Jye's hat and t-shirt, and sit with a detective in a nearby park for a long time.

"But nothing ever came of that," Mrs McWatters said

Late in 2018, detectives submitted a brief of evidence - everything they had after the first three years of investigation - for review by the coroner. With that review ongoing, police have re-issued their appeal for information. The investigation is continuing. But for the McWatters it has gone all too quiet, the updates from detectives all too sparse.

It's a frustration shared by Lake Illawarra's Detective Senior Constable Phillip Brown, who heads the investigation into Jye's murder.

"I've been living it for five years; I think about it all the time," he said. "It's frustrating that we can't do more. We've done so much with it; so many strategies targeting different people ... it just comes to a bit of a grinding halt. Then it gets a bit more life and we've got a chance to do other things, then that dies out. Then someone else comes forward ..."

After so long, the detective knows well the boy who will be forever 19. He has had time to study Jye, and to understand better than most the extent of what has been lost. "He had the rest of his life ahead of him and it's been snuffed out, just like that," he said. "And no one really knows why."

"He wasn't a big-time criminal; he was a kid. A naughty kid, who was doing what everyone else was doing in that area - nothing to be shot in the back of the head for and left in the front yard to die. It's terrible. He wasn't a bad kid."

Mrs McWatters was at Jye's side one night in April 2015 when he went to answer the front door and was set upon by an teenage boy with a hammer. Jye was hospitalised by his injuries; the teen was charged and dealt with in the children's court. Mrs McWatters later learned the boys' conflict had originated at a party.

"His [the attacker's] girlfriend had walked past and Jye smacked her on the bum," she said.

After that incident, Mrs McWatters warned Jye against opening the door without knowing who was on the other side. But he'd tell her, "don't worry Nan, everything will be alright".

"Do you know why I don't think it was a boy or a man [that caused him to go outside the night he died]?" Mrs McWatters said. "Because after the carry-on with the [hammer] I used to say to him, 'Don't ever go to the door'."

"The first thing he used to do when he got out of bed was put his cap on. Always, the hat went on first, then the shoes.

"But he was found in not even a t-shirt. Just a pair of little thin board shorts that he used to sleep in. I think a girl came to the window and got him out.

"He always fooled around [with girls]; he must have fooled around with the wrong one."

Mrs McWatters raised Jye and two of his three brothers when her daughter Sonia, could not - an unconventional arrangement borne of personal family matters of loss and heartache. Sonia remained in the boys' lives until she passed away suddenly in August last year. The Mercury understands police are not treating her death as suspicious.

Jye's eldest brother Dwayne McWatters said Sonia spent her final years tormented by her son's unsolved murder.

"It was like a rocket going into the ground," he said.

Jye's second-eldest brother Dale McWatters was in jail when both Sonia and Jye were laid to rest. Dale, who has been convicted of serious knife and drug supply crimes, wasn't granted leave to attend the funerals.

Jye made no secret of the fact he smoked pot. But he was not into anything more sinister and he was not caught up in any of Dale's activities, Dwayne insists.

"They were at opposite ends of the spectrum," he said. "And I'm sure Dale would have heard about it, if [Jye's death] was about him."

"There's no possible explanation [for Jye's murder] that I can come up with."

The McWatters have become used to fielding rumours from friends and strangers. Dwayne says he doesn't go a day without hearing one.

Dwayne thought Jye was asleep in his room on Boxing Day 2015, when he instead found his brother's cold body outside. He can't forget the sensations of that morning. For him, nothing has been the same since. He dreams about all his dead relatives, but mostly he dreams about Jye.

"When I grabbed him in the morning, he was like a plank of wood. It was like I was lifting up a plank of wood because he was so stiff," he said.

"It's sort of surreal still to this day. It's as if it's a bad dream and as if when I wake up, I'm dreaming. It's as if this isn't reality because it isn't how I used to feel: whole."

"Every day you think, when's this sh*t going to end? And when am I going to see justice?

"It might be easy for [the killer] to live with it, but my family's the one that feels it every day. What's guilt compared to grief?"

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Anyone with information that could assist police is urged to contact Crime Stoppers on 1800 333 000 or visit https://nsw.crimestoppers.com.au. Information is treated in strict confidence.