Work has restarted at the Waihi gold mine where a worker was killed last month and a probe into the death has begun, the union says.
Tipiwai Stainton, 29, was killed when his front-end loader rolled down a "stope", or mined out void, about 200m beneath the surface at OceanaGold's Correnso mine on July 28.
The mining union, E tu, says it is fully involved in the investigation into the death, which began this week.
An Australian consultant on Monday concluded interviews with employees who are part of the investigation, says E tu organiser Myles Leeson.
The company is now waiting for reports on the bogger, or loader, which Mr Stainton was operating at the time of his death.
Part of the site has reopened and the realities are hitting home for workers.
"They're back at work and Tip's not there, so they're having to deal with that," Mr Leeson said.
The company will report its findings to Worksafe once its investigation is complete.