A year on from most parent's worst nightmare, the mother of Mike Zhao-Beckenridge is still holding out hope her son will come home.

Mike and his stepfather John Beckenridge were reported missing a year ago from Invercargill.

There last known sighting was at the Tokonui gas station.

Police still working on the case have stated they won't refer the disappearances of the two to the corner just yet.

Acting detective senior sergeant Stu Harvey says they understand the frustration from the family.. but investigators won't give up.

"Mike's mother's always hoped that he's alive. As far as I'm aware that continues to today.

"Our investigator staff are hopeful that that's the case as well, but we're keeping a really open mind about what's actually happened".