Three teenagers were questioned by Lake Illawarra police yesterday evening following a fire at the abandoned Minnamurra mansion.
Rural Fire Service units from Albion Park and Dunmore as well as Fire and Rescue NSW units from Kiama and Shellharbour were called to a "minor fire" at the incomplete Dunmore Equestrian Centre just after 4pm yesterday.
On arrival, RFS members apprehended three teenagers who were held until police arrived.
The 2000-square-metre mansion was about 70 per cent complete when work ground to a halt four years ago after John Kosseris's Belmorgan companies were placed in receivership owing tens of millions of dollars.
The future of the unfinished residence remains in limbo, complicated by court orders to restore environmentally sensitive wetlands that Mr Kosseris estimates will cost $4 million.
Last month, Mr Kosseris told the Mercury there had been well over $1 million of vandalism to the property, while another $2.5 million was needed to complete the project.