On Thursday, chief prosecutor Lars Lundin decided to open an inquiry into suspicions that the project breaks working environment legislation.
At an inspection of the building site, the Swedish Work Environment Authority discovered several health and safety failings.
As well as Göran Persson and his wife, Persson’s brother could also be charged with breaking health and safety laws. His building firm is carrying out the work. All three could face fines if they are prosecuted.
When the initial findings were submitted to the prosecutor in April, the prime minister said that the failings were a pure oversight on his part.