A 46-year-old man has been charged with murder as well as arson following a fire in which two people were found dead in Dunedin in January.

The fire destroyed the Wesley St house David Clark and Anastasia Neve were in but police believed the pair were dead before the blaze began.

The man is due to appear in Dunedin District Court tomorrow on one count of arson and two counts of murder.

Police formally laid the murder charges earlier today at the Otago Corrections Facility.

"This is a significant milestone in the investigation, however, the dedicated CIB team still has a lot of detail to work through in order to ensure a robust, fair, and thorough investigation," Detective Inspector Steve Wood said.

"We know the arrest for murder will assist concerned members of the community, and help the families and friends of the victims feel safer as they recover from their ordeal."

"The families of David Clark and Anastasia Neve are aware of the arrest, and say they are relieved and thankful."

Phone Dunedin Police on 03 417 4800 or call Crimestoppers anonymously on 0800 555 111 if you have information.