New South Wales authorities will conduct a fresh inquest into the death of Mark Haines, a 17-year-old Aboriginal boy who died after he was found on train tracks south of Tamworth over 35 years ago - 16 January, 1988.

Mr Haines' uncle, Don Craigie, has long campaigned for another investigation into his nephew's death, reiterating his call for justice on 16 January every year.

In 1989 the first inquest returned an open finding.

In a statement before the new inquest was announced, Mr Craigie said the initial investigation that was conducted into Mr Haines' death has been shown to be "completely inadequate".

"We cannot get the answers or the closure that we need until this is resolved," he said.

After the news of a new inquiry, Mr Craigie told NITV News the family has consistently said "the evidence does not support the police theories".

"Although I cannot say we are overjoyed [by the fresh inquest], we are relieved," he said.

The New South Wales Crown Solicitor's Office wrote to the family's lawyers, the National Justice Project, last week to confirm a new inquest would be held.

National Justice Project solicitor Karina Hawtrey told National Indigenous Times that their clients "have been seeking this inquest for so long".

"After so many years left without answers, now they will have the chance to secure answers about what happened to Mark," she said.

"We will stand with our clients through the coronial inquest process as they seek truth, justice and accountability."