The mother of a teenage boy who tragically lost his life during a sleepover has expressed her relief and gratitude after justice was finally served, nearly three decades after the incident.

The tragedy struck when her 13-year-old son suffered severe burns after becoming trapped on the top floor of a house engulfed in flames. He succumbed to his injuries 11 weeks later in the hospital.

Following a thorough investigation, authorities concluded that the devastating fire was intentionally set.

After a prolonged period of over 27 years, Gregory John Walker has now confessed to unlawfully causing the schoolboy’s death. His admission came on Wednesday, as he stood before the NSW Supreme Court.

With a simple but profound statement, Walker said, “I’m guilty, Your Honour.”

Julie Szabo, the boy’s mother, described hearing this admission as the moment she had been waiting for. The news brought a sense of closure for the loss of her lively and beloved “mummy’s boy.”

“All I ever wanted was the truth and he’s finally admitted it,” she said outside court.

“I’m so grateful justice has been served.”

Szabo thanked police for never giving up on the case and leaving no stone unturned in the nearly three decades since her son’s death.

“This is the biggest day of my life,” she said.

“We’ve constantly waited for this day and we thought it would never ever happen.”

She’ll be marking the occasion by visiting a tree she planted in her son’s honour and decorating it with flowers.

Police in 2020 increased the reward for information in the cold case from $100,000 to $1 million, hoping it could finally lead to a conviction.

Walker was arrested in 2022 and charged with murder and two maliciously wounding offences.

But, after his trial was postponed the day it was to start, he pleaded guilty to the lesser charge of manslaughter on Wednesday.

A second charge of maliciously inflicting harm on another person will be taken into account on sentencing.

The 58-year-old will return to court in November for a sentencing hearing.