A Subiaco charity has unravelled a two-year mystery after investigating their sky-rocketing power bills and a strange muffin smell by setting up a security camera inside their communal kitchen.

Post Newspapers managing editor Brett Christian told 6PR's Simon Beaumont the Subiaco-based Earthwise charity had long suspected something was afoot.

The man was using all his own ingredients. (file photo) Credit:Rodger Cummins

"They discovered their power bill had gone from around $100 bucks, to $400," he said.

"So they looked back over their bills and they realised there was a pattern to this. They started to make some inquiries around the neighbourhood, and some office workers said that they could smell muffins cooking – sometimes very early in the morning.